That shop isn't at Downtown Disney anymore - it used to be along side of the AMC theatre just across the alley from Disney Quest.
But it is still in operation in Orlando. I'm pretty sure that it's called George's Guitar Gallery, or at least something similar to that, and there are several stores in Florida. The one in Orlando is somewhere off International Drive, but I don't recall just where. I'd guess that a google search would pull it up.
Dick Taylor