StockX, was created for probably the most unique reason ever, to give the $1.2 billion (U.S. only) sneaker resell market the opportunity to reliably understand the actual value of their investment in a pair of sneakers.
Besides the need for sneaker heads to have real-time data on the value of their sneaker from a centralized source, StockX also provides assurances against fakes, which not something eBay is known for. At the moment StockX is not available for international users, but with a further $6 billion resell market in the rest of the world that will probably be likely to change in the near future.
The founder of Campless and StockX, Josh Luber, wants to help the sneaker resell game move closer to the stock market than the drug trade which it was/is very similar to from a market dynamics perspective.
Check out his TED talk (below) about the sneaker stock market then head to StockX to start playing the market.