One guy from a band I was in did pitch perfect R2-D2 impersonations with his. I could get various "Harpo Grouch" esque noises, but not much more. I HAVE seen people who have put the practice in do some serious work on it, but it's sorta like the kazoo - it doesn't matter how much you practice, or how beautiful it sounds. It's always going to be an awfully silly instrument.

As to the frog... band I was in has a 'rhythm frog' player in it. Silliest thing we'd seen, so on the spot we swore we'd write it in to a set. I don't know about local shops, but I've seen them forever on Lark in the Morning. They aren't TOO rare, though. Local music shops may have one or two that they buy just for the comedy value.

M