Creating an App for Selling Sports Cards?

[Mormi08]

Hello, recently I've been interested in creating an app and website. that would enable individuals to buy, sell, on the app and on the website itself. I would like to know opinions on this, and what should the app include to keep everyone happy and safe with the app itself. What should we add that's different than other sites such as ebay? (btw this site is strictly to sports cards) and the fees will be much less than ebay.

[mjohnatgt]

Very crowded space already. Your competitors are:
eBay
Beckett
COMC
Justcommons
Sportlots
About 50 different auctionhouses of various sizes
The Pit
Craigslist
This website
Other message boards
Facebook groups
Amazon
And then there are the sites which try to catalog what's going on at other sites.

Maybe write a bot that captures all eBay sales values of cards over time and show trends, like a beefed up worthpoint.