I'd go E36 or E30.
I have a friend who found a E30 325is on Craigslist for $800 in pretty good shape. So far he has it pretty well speced out, rebuilt the engine and got a new paint job on it. He's spent just over 5k including the purchase price of the car.
2009 E92 M3 /// Melbourne Red /// Fox Red /// M DKG
Full Innotech Exhaust - DINAN Intake - IND Engine Bay Appearance - IND Hand Stitched Boot Covers - and much more....