Billed as "the stock market of things," StockX is an online marketplace that offers items for sale at prices determined by live metadata. Basically, if demand for a certain piece of clothing rises or falls, so does its price, just like stocks on Wall Street.
So far, the site only sells sneakers, and its purpose isn't to help you snag the best deal, but rather to get a fair market value for footwear. Relying on historical data visible to both sellers and buyers, StockX has a certain level of transparency that you won't get from eBay or resellers.
This obviously makes sense for buyers, but it's not exactly clear why a seller would agree to it when they can just grossly over inflate their earnings elsewhere. Have an extended read over at TechCrunch.
StockX is run by the good people at Campless, who provide date for our quarterly sneaker reports, by the way.