This is more of a programming question. Obviously the site used to use ebay sold listings to calculate values for the brickfolio.  A recent comic book app has split ways with another company that supplied them with sold comic book values.  In terms of difficulty, how hard is/was setting up a system that records ebay values?  I assume you have to pay to get the data from ebay then design you own program to calculate values?  How long did this take and how difficult was it?  

9 hours ago, stackables said:

This is more of a programming question. Obviously the site used to use ebay sold listings to calculate values for the brickfolio.  A recent comic book app has split ways with another company that supplied them with sold comic book values.  In terms of difficulty, how hard is/was setting up a system that records ebay values?  I assume you have to pay to get the data from ebay then design you own program to calculate values?  How long did this take and how difficult was it?  

This used to be easy, as there was a findCompletedItems() function in the Finding API. The Finding API just requires a developer program account, which most anyone can get. They removed the above mentioned function from it last year, and this functionality is only available (in API form) in the Marketplace Insights API, access to which is heavily restricted.

Unless you can convince ebay to give you Marketplace Insights access, which you almost certainly can't, then you would need to be scraping this data. Old school would probably work (plain HTTP requests), doesn't seem to be much JS going on in the search results page, new school using automated testing tools I would advise against, ebay would likely detect it and block you (my advice against is not because you would then be blocked, but rather that you would be wasting your time).