I would like it if when searching for a game it would bring up the pal and Japanese versions of that game as well. Having to specially  search under those tabs and scroll down to find them is a hassle. Also if your searching for a game title and a bunch of comics and cards pop up. Have it where you click on the games tab and it removes all but games, cards, comics, ect...

THe booster packs and box are there but no listing for the starter decks

In addition to uploading pictures of the case and manuals, also integrate 3D models, viewable in-website if possible 

For the base set Pokemon booster packs, separate the packs based off the Charizard, Venusaur, and Blastoise pack arts. The Charizard is worth much more than the other two and throws off the values. 

Since some collections are quite valuable, they are a useful part of the net worth to consider for some people. This would make it useful to add external API usage by financial trackers like Monarch Money, so that transactions (collection additions/subtractions) and balances over time can be viewed.

Many store would pay to save time for creating item plus it would help the sync