Not 100% accurate I know, but back in December my dealer (the only official one) in Holland said he had sold about 50 A500s and 30 GPAs. He said Fiat NL were aiming to move about 1-200 A500s per annum.
Considering in Holland that a manufacturer needs to sell about 6000 units before you begin to see that model every day, I think its fair to say we will remain in a pretty exclusive club.