I'm on my second E36 M3 sedan. Bought the first one six years ago for $16k (at the time it had 70k miles with lots of records) and this one a few months ago for $7k (122k miles and lots of records, plus a few mods.)
The $7k car has seen 3500 miles so far with no issues and not much maintenance - preventative waterpump/thermostat, preventative alternator due to noise, plugs and valve cover gasket that it needed, oil change that it needed, wheels/tires that it didn't really need. It did 206/211 on a Dynojet which is about right for a stock one. I put 1600 miles on it the other weekend with no issues so it could sit in the GRM paddock at the Rolex 24, in fact. Pics: http://www.facebook.com/media/set/?set=a.10151038371665602.776935.811445601&ty...
They really are cheap now, but instead of buying a $5k rat I bought a $7k car that wasn't 100% perfect (drivers seat worn, a few dents/scratches, signs of front air dam repaint, small spot of rust by the rear license plate, etc) but ran great, because I was looking for a beater/driver not a showcar I was afraid to take out of the garage. And I have no regrets.
I do see this turning around eventually, as it did with various E30s worth having (the same short bumper '90 325is I bought for $1900 in '03 would now be worth $4k+.) So I'd recommend buying one sooner rather than later. And of course buying the nicest one you can possibly afford. If you get a good one, they're great cars! If you don't, prepare to be nickel and dimed forever...