50-300 coins and give them out (maybe all-expenses-paid or maybe at cost) to users who meet some to-be-determined criteria
Preferably a .999 silver coin. It would be cool if it came with a 1 BTC denomination (unloaded ofcourse).
I guess that there would be a demand for 2 versions - one possibly silver, at a cost and one cheaper to manufacture (brass? maybe even plastic?) for the users that meet certain criteria and just want a souvenir.