OP, I mean this in the best possible way, and I can definitely relate to an M3 pulling at your heartstrings, but if you're struggling just to come up with half of the purchase price of the car, you have a very high chance of regretting buying an M3 and growing to resent it because of how much it will force you to pay to maintain it even compared to a 335i, never mind a "regular" car. Keep in mind that no matter what purchase price you find for an M3, you'll always be paying the maintenance costs of a $70K high performance car. I would also argue that an M3 is not a great first car to own, and if you'll just be DDing it on city streets and freeways, a lot of the value of the M3 that you're paying for is going to go untapped since I'm assuming that your budget doesn't currently factor in any track events.
Which leads me to my next point that's already been made by people earlier in this thread. If your heart is set on an M3, then even though a 335i is an absolutely outstanding car for DD duty, sporty back road driving, and even the occasional track day, YOU probably won't be happy with it. You'll feel like you settled, and every time you see an M3, something will eat away at you on the inside -- so I would advise YOU to avoid that option, because a 335i is also an expensive car to buy and not be happy with.
Which leads me to agree with the others on here: Buy a fun, much less expensive car and enjoy that until you have the means to cover the total cost of ownership on an M3 yourself. You're lucky to live in an era that's chock full of fun, fairly inexpensive car options: Civic Si, BRZ, Miata, Golf GTI/R, MazdaSpeed3, Ford Focus/Fiesta ST (yes, seriously), Mini Cooper, LanEvo, WRX or STi, Mustang GT -- the list goes on. Any one of those will bring you a ton of smiles per mile at a MUCH lower cost.
And I'll go ahead and say it: If you haven't already learned how to drive one, just getting a car with a manual transmission can turn even an ordinary car into something that's fun to drive.
