whoa, take it easy B
i would definately think this one over, A LOT
BMW's are cool and all, but they also suck ass
isn't the M3 real wheel drive? and you live in a snowy area?
i had a 325is and that thing was cool for sliding the rear around but absolutely sucked balls in the snow, bad choice for a north eastern resident...
maintenance costs are out of control, price a set of plugs and ESPECIALLY plug wires for the car... the motors and drive trains are pretty dependable and well built, but when something does go wrong you are in for a world of expense to get it fixed...
also price your insurance before you get it, full coverage for a "sporty" bmw is gonna be an ass load of money
and you also gotta remember you are still looking for a house sometime in the future too...
edit: if you do decide to get it be sure to pull a compression test to make sure the top end isn't played...
valve jobs = $$$