What's it worth? - eBay item value calculator

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Jan 21, 2011, 9:44:18 AM via Website

Hi Folks,

great, that there is a board where you can present your own apps :)
I'd like to take this chance and present you my little project.
After presenting my app in the german forums, it's time for the english translation ;-)

I'm frequently selling stuff on eBay and every time before I do that, I search the completed items to find out what I will earn.
When I wanted to do this quickly on my phone I had to open the full web view of the eBay site, which is terribly slow and unusable on small devices.
So I always wanted to develop an app that does this for me with a simple user interface and only one click.

As soon as I got my Samsung Galaxy the development began :)

After weeks of work I finally got a working version of the "eValuator" or smoother "What's it worth?".

The app does exactly what you are doing, when searching in the completed items.

- You log in (you have to be logged in, to view the completed items)
- You enter some search terms
- You select a category to refine the search, because the search terms are ambigeous
- You select an item condition matching the item you want to sell
- You take a look at the prices and try to estimate an average price
- You ignore items that are described as defective or demaged

There you go: You know what you will probably earn :)

In my app you have it all with just one click:

Here you already see the median (mean value), which is more accurate than the simple average value, since it is not as strongly affected by single very low or high values.
If you want to read more on this -> Wikipedia (Median)
Below that you see the median including shipping, which is the real market value, or the value people are ready to pay for that item in total.
The last line shows the overall price range found.

Now you can restrict your search to a sub-category to get a more accurate result, or view the results in detail.

By clicking on one entry in this list you can open it in the android browser.

To handle the "ignore defective items" aspect, you can specify a permanent auto-filter, by entering the words you want to ignore in the settings.
All items containing these words in their title are from now on cropped from the search results and so no longer can affect the median value, making it more realistic.

Also you can specify how many items should be loaded with every search.
25, 50, 100 or 200
Doing so you can choose between faster loading and less traffic, or better and more accurate results based on a broader data set.

The app works for ebay.de ebay.com ebay.ch ebay.at and ebay.co.uk

Searching in completed items is only possible after logging in, so this app will need your eBay account.
I hereby promise, that this data is only used for the login and for nothing else.
It is not accessible to me or anyone else, it remains on your device and it is not sent anywhere.
Also it is stored in a secured memory area that is not accessible for other apps or via USB cable (see Android File API).
If anyone still is worried, I invite you to Dortmund (Germany) to go through the source-code with me ... free coffee included :D

The FREE version is available on the official market for free.
It is restricted to searches in Buy It Now items, but includes all features, so you can test everything before buying.

Here are the Links to both apps including the QR codes to the android market:
What's it worth?
What's it worth? FREE

I would appreciate constructive feedback of any kind!
The FREE Version is actively used by about 1000 users but only a few users left any feedback :(
And...of course...there are always some haters, just rating 1 star without any comment and not even giving a reason :(
Kind of frustrating to see your "baby" bashed just for fun as a developer :(
Funny to mention, that this is the case only for the free version...the full version got only 5 star ratings so far...leaves me with the conclusion, that there are people out there installing free apps just to destroy the ratings.

If you like it please leave a positive feedback on the android market! My further work depends on it!

Have fun using this app :)


— modified on Jan 21, 2011, 10:19:46 AM

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Jan 21, 2011, 2:34:44 PM via Website

Douglas Carter
Well, I tried to make an eBay account, but with no US credit card number, it won't let me complete registration. Therefore, I can't get past the first stage of your app.
I don't quite understand :)
You weren't able to make an eBay account, or you weren't able to login using my app?

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Jan 22, 2011, 2:29:26 AM via App

Looks like a very useful app. I'll give it a try and let you know what I think of it.

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Jan 26, 2011, 7:45:45 PM via Website

Rafael K.
Douglas Carter
Well, I tried to make an eBay account, but with no US credit card number, it won't let me complete registration. Therefore, I can't get past the first stage of your app.
I don't quite understand :)
You weren't able to make an eBay account, or you weren't able to login using my app?

I was not able to make an eBay account because I need a credit card number. I have an EC Karte, but not a credit card. I think I need a credit card to sign up for eBay

  • Forum posts: 775

Jan 27, 2011, 6:51:12 AM via Website

I tried your app and I was able to log in with my ebay account. I found that some of the things I tried searching for showed only 5-20 results, when if I searched them on ebay website they showed many thousands of results. So I'm wondering how reliable this app is? Do you know why it's finding fewer results, am i doing something wrong? For instance if I search "Amp" with your app with condition "all" and category "all" it shows 23 results for buy it now. I have the app set to return 200 results, I couldn't find how to change the category. An ebay website search for "Amp" returns 172,051 results, so why is the app not returning at least 200? I still think this is a great idea for an app though!

— modified on Jan 27, 2011, 6:56:34 AM

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Jan 27, 2011, 7:10:04 AM via Website

This is the expected behavior :-)
The app loads the first page of results with a maximum of 200 items, according to the setting you made.
It reads the items and select only those, that were really sold (green price).
That's why it is not always necessarily a total of 200 items, that the average is calculated from, but the successfully sold items are the only items of interest.
It is not relevant for the current market value of an item if someone lists it for a price of 5000 but it never gets bought for that price.
Only what people are willing to pay for an item defines the market value.

If your query is specific enough (of course amp is not) this is a set of prices big enough to get a representative average price.
Loading all pages would take much more time, but would not improve the result from a mathematical point of view :)

Try a more specific search, like “iphone 3gs 16gb“.
amp delivers too many different amps from too many different brands in too many price classes, making an average price totally meaningless.
Just as the average price of all Smartphones would be. It wouldn't tell you anything on how much you might get, when selling for example a "Samsung i9000".

But if you want to sell for example the "iphone 3gs 16gb" mentioned above and search for that, then go to the appropriate sub category, to take items like cases for 1$ out of the equation you will get a really useful result.

Hope that explanation helps :)

— modified on Jan 27, 2011, 8:36:49 AM

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Jan 28, 2011, 9:46:11 AM via Website

Oh, that makes sense now. How long do sold items stay available for view on ebay? Is there any way to get a broader sample? Searching for the generic "amp" showed only 27 sold items, but theres over 170k total items listed. I guess if the sold items only stay viewable for a short time, then you cannot get a large sample?

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Jan 28, 2011, 10:01:44 AM via Website

I think the items are available for 3 month.

If the query is specific enough you don't need a big sample set to get a good result.
It doesn't really affect the value if you have a set of 1000 or 20 samples if they are all of equal or at least similar type.
The distribution for a specific item stays the same, so the average doesn't vary significantly.
To get a bigger sample set you would have to load several pages of the search result, each about 250 KB in size.
This would work on a stationary PC with DSL connection, but not on a mobile device, which has only 5KB/s in the worst case.
Even loading ONE page takes a long time then.

As I already said, amp is a really bad example.
The result you get has no meaning, because there are amps for home audio, there are amps for car audio, there are amps for 1$ and there are some for 10000$.
You get a number from the app, but it is completely meaningless. It doesn't tell you anything about the market value of ONE SPECIFIC model.
But when selling something and trying to estimate the possible profit, you have a specific amp with a specific name and model you can search for.
That would be an adequate test-case for the app, since it is made for exactly that purpose :)

  • Forum posts: 775

Jan 29, 2011, 9:13:13 AM via Website

Thanks for explaining it better. Maybe you could let the user choose an option of how many pages they would want to search? On my phone the search only takes a couple seconds, and if I am looking to sell something, I'd be willing to wait a minute or more to get a large sample.

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Jan 31, 2011, 8:22:32 AM via Website

Hi Jeremiah,

I'll think about that. When used in a WiFi network the loading of more the one pages shouldn't be a problem.
There are also some new features I am currently planning, that would probably benefit from a larger sample of items (especially auctions).


  • Forum posts: 3

Aug 15, 2012, 11:07:51 AM via Website

This app is AWESOME!! You have saved me hours a day looking up completed listings. I own a small business where we buy, sell, and repair used electronics. Throughout the course of a day, we have to go in and look up hundreds of items to determine what we can pay the customer to buy the cell phone or other device that they are trying to sell us. I used to spend literally hours a day doing this.

Your app is great, and it saves me tons of time, but It would be great if it was available for iPhone or if there was a version I could use on my PC. Right now I have a galaxy tab to be able to use this app, but this is an inventory item that we bought to resell, so once it sells, I will not be able to use your app anymore being that i have an iPhone. What are the chances of you coming out with a version of this app for iPhone? My iphone is also jailbroken, so is there anyway that I could make this app work on my iphone or would somebody have to change it and put it on cydia for me to be able to do that? I know that being jailbroken, I can install apps that would normally only be available on android, but I think this is because somebody put them on cydia and made them compatable.

Any advice or information on this would be very helpful. Thank you.

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Aug 15, 2012, 11:21:39 AM via Website

Hello Nick,

thanks for your great feedback!
Currently I have no plans of porting this app to iPhone, simply because it uses totally different technology and I would have to buy the hardware for development and testing (iPhone, MacBook). That's simply "not worth" the effort for me :)

But there is a (slightly complicated) way you can use the app on your PC. At least the free version.
The Android SDK contains an Android emulator on which you can install and run apps.

You should find a lot of tutorials on google by searching for: install apps on android emulator

Something like this http://www.botskool.com/geeks/how-install-apk-files-android-windows-sdk-emulator

Good luck! :)

  • Forum posts: 3

Aug 15, 2012, 11:31:51 AM via Website

Great, thanks alot man. It would be nice to have it on my phone, but as long as I can at least run in on my computer I will be all set. Thanks a lot man. I will get that setup now. Much appreciated.

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Aug 15, 2012, 11:38:52 AM via Website

Great! The following should work best, once you have the emu running:

- Open the browser in the emulator
- Go to androidpit.com
- A prompt will appear asking you if you want to install the app center -> do it
- In the app center you can find and install the app

In this way you will also get all the future updates.

— modified on Aug 15, 2012, 11:39:37 AM

  • Forum posts: 3

Aug 15, 2012, 11:54:11 AM via Website

Cool. That sounds easy enough. Thank you!

  • Forum posts: 2,303

Jan 2, 2013, 12:33:08 PM via Website

Hey guys!

For everyone who missed out on this app, because he had no Android device:
There is a totally new mobile website version: evaluator-online.com
Now the eValuator can be used, no matter what device you own.

Please note, that the site works well, but is still under construction.

Enjoy! :)

  • Forum posts: 12

Feb 12, 2013, 3:00:36 AM via Website

This app is really nice. Thanks for the web version too!

  • Forum posts: 1

Apr 15, 2013, 2:12:45 AM via Website

I love it, I am not a developer. I volunteer 2 nights a week running a Pokémon Trading card game league.
One of the hardest things is to protect the younger kids for the serious players who will try to trade them junk for valuable cards. This will really be helpful, I have been researching how to create an app like this, and have been searching for code examples. Great job!

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