You'd have to buy a lot of pie crusts I think. You can buy 6-inch flour shells all over the place here, but I live in a pretty ethnically diverse area (ailes of Goya folks) so I don't know where you could get them. They're not called empanada shells though. They'd be in a refirgerated section, they're not as thin as tortillas, but they'd probably be with them.
That's my only suggestion.