I`d rather have one item in the shop at my will. Give every user 1 (one) free item in the shop if the community manages to hit the barrier of 1.1mil. games. I don`t want steampunk electrician or anything else which the entire community can have, for that matter. Give us the choice of 1 free item in the shop and then you have my shield.
Assuming we can win... The game would be overly saturated with those items since all the active players will probably play at least one game. There should be more prizes for people who play more (like someone already mentioned, incentive for more than 1 game), otherwise the items just become commonplace, overused and uninteresting. I like the initial idea tho and I look forward to playing lots... which I already do.