I bought my '90' M3 in November of 2003, paid $16,500.00 Cdn (about $12k Usd.) The car had a number of problems, broken sway bar links, bad brakes, leaking windshield, and major electrical problems, but inspite of them, the good out weighed the bad. The car had 211,000km. (131k miles give or take) and like most M3's had been thrashed pretty good.
Good points....the engine had been recently rebuilt and seems very solid. J.C. chip, ported and polished head and intakes, EVOIII cams, Hartge suspension and wheels with Kumho tires.
So far I have replaced the front sway bar links, reinforced the rear sway bar brakets and replaced the links. New pads and rotors all around. Car came equipped with an aftermarket daytime running light module which was causing most of my electrical problems so it has been trashed.
As far as I am concerned it has been money well spent and wouldn't trade it for the world. Heading down to Mid-Ohio next weekend for the Vintage races so this will be it's first major outing.
2004 Kia Sorento