Estimates based on premiums in other countries have already been posted throughout this forum. Depending on which country you look at the M3 in the US could cost between 55k and 65K.
Also, the talk that BMW is delaying the release of US pricing is ridiculous. BMW priced this thing a long time ago. There release of pricing in the US will follow the same flow it did in Europe. Expect to find out the price here a few months prior to the beginning of production for the US.