This t-shirt featuring Star Wars silhouettes is originally a creation from Super7Store.com. Like most of Sheldon's shirts that originate from there, the thing appears to have vanished as soon as we (well, me, at least) even heard about its existence. If they restock or I come across a replica anywhere, I'll be sure to update. Sorry!
Featured on The Big Bang Theory episodes
S10 E04: "The Cohabitation Experimentation"
S11, E23: "The Sibling Realignment"