I think Mercari should be used to check prices against in the market as they are becoming a heavy hitter for resale.

It'd be awesome to be able to see a list of games in your collection that have have recently increased or decreased in price. I love logging in and seeing that my collection's value has increased, but it's a little frustrating that I can't see why that value is going up (or down). 

Perhaps the list could be could be sortable by biggest increase/biggest decrease as well? 

Would be great to filter by items that are on your Wishlist or not in Collection on the eBay Game Sniper Tool.  So you can filter out all items that you have already and only get alerts on items that you are looking forl

Since the Saturn's Japanese library is so much larger than its American/PAL libraries, and since there are large price disparities by region, I would love to be able to track the prices of Japanese imports for the Saturn.

I would like to see something like a price check app that bloops up when looking at ebay listings. I don't know if I'm explaining that right, but as an example say you're looking at a Super Mario Bros. listing on ebay for $15, the plugin would bloop and be like "we have this item valued at $5 and rising" or whatever

There are a lot of results in the eBay Game Sniper tool that are incorrectly matched. For example, a listing explicitly stating it's for the Xbox 360 version of a game being matched to the Xbox One version in the tool. Listings for demo discs and loose manuals are also often matched as the actual game. If refinement of the tool is planned in the future, it might be beneficial to start compiling a database of matches flagged as incorrect, which we could add to by using a "report" button.

Include pricing and such for DC comic cards. I've got a few sets outside of the Marvel ones, I'm sure others do as well.

Add One Piece Japanese TCG