I dont think they had the 328i in 1982...
Ive had my 1998 328i since May 4th, 2005. I purchased it with 154,000km on it and as of this morning is sporting 266,850 km on it. In that time I have replaced the water pump, thermostat, fan clutch (x2), tie rods, brake rotors/pads, all four struts, hood release cable, three door lock actuators, power steering resevoir, valve cover gasket, spark plugs, fuel filter, and not to mention the countless oil changes.
This may seem like a lot reading that, but that is through NINE YEARS of ownership and 112,000 km. The most expensive of that list was the struts, followed by four rotors and pads ($750).
It is entirely possible to get a $4,000 M3. A friend of mine bought a 97 M3 Sedan for $3,900 recentley (Canadian Pricing mind you, probaly $3,000 US). So far has removed the tacky shit the previous owner had done, replaced the spark plugs, valve cover gasket, and fuel filter and has a decently running M3. Its not in the best shape, but hell its still an M3 and pulls like one. And you have it better then us because you dont have to worry about rust as much as we do.
You do need to remember your buying a 15 year old car. Even a brand new Ferrari has problems. Ive seen a 4 year old Ferrari in the shop because the transmission blew up costing $13,000 to fix. Ive seen an 06 Ferrari 360 Modena need to be towed 300 km because its transmission shit the bed. People dont keep Ferrari's past 80,000 miles. People keep BMW's past 200, 250, 300,000 miles for a reason.
Theirs a guy on Bimmerforums that has a 325i with 600,000+ miles on it. Ive seen the odometer picture.
Honestly, try to scoop that black M3 Sedan. It looks in good shape minus a few things, but none if it is huge. All of it can be fixed in time with some patience and money.
I will probably never own an M3, or an M5. My next BMW is the only one that can outrun the E39 M5 in the standing mile....
This is mine btw: