In the ancient days of sports merchandising, fans could buy jerseys of only the biggest stars. Eventually leagues began selling customizable jerseys online, but that couldn’t reach the fans most willing to buy—the ones attending a game who are pumped about, say, a hot new rookie whose jersey isn’t on sale in the building. Now Silver Crystal Sports is capitalizing on that gap: It makes build-your-own-jersey kiosks for 400 worldwide partners, including NFL, NBA, MLB and NHL arenas, and is increasing game-day jersey sales by between 25% to 150%. Last year, it even began rolling out an app so that fans can customize their jerseys from their seats and have them delivered 20 minutes later. "We’re actually beating the Internet," says cofounder Adam Crystal.