Dave gave good advice on the financing aspect. The other thing you need to check out is whether or not your insurance company will insure a rebuilt vehicle. Most will not.

That M3 was obviously worth quite a bit of money prior to the loss. That being said, the car had to sustain a significant impact to meet or exceed 80% of its value to be deemed a total loss. I'd stay far, far away from that car. Who knows if that car was fixed correctly? Would you really sacrifice the safety of your self and your occupants for a few thousand dollars?

I'm willing to bet you can find a slightly higher mileage '01 M3 for around $25k that doesn't have a rebuilt title.