where do you live? I know in Northern California you can find shops that sell you rebuilt M3 engines. Or try junk yards for the engine.
Also youll need a transmission(i think), the wiring harness for the other engine, an exhaust setup.
How much are you looking to spend. You need as much as you want i guess.
We all get the urge...Saturday early morning...nothing to do till noon...
The aural sensations of 1st gear WOT
**CGM **(Certified Garage Mechanic)