From concert t-shirts to Air Jordan sneakers, fashion has become a popular collectible category worldwide. In fact, every year collectors spend billions of dollars buying rare and collectible sneakers alone. Sneakers have become so popular, standalone digital marketplaces like GOAT and StockX have emerged to serve the growing secondary market. In addition to graphic tees and limited edition footwear, other fashion items often collected include vintage denim, military uniforms, and of course, watches and jewelry.