Hey guys, thanks again for all the good answers!
Soo I have a little problem now. Last weekend I found a '94 325is, black on black with all the goodies. Really good condition too, and only 130k miles. Leather seats looked like new (had seat covers on for most of the car's life). Everything in perfect order. All the usual things that break had been replaced recently (i.e. new radiator, thermostat + housing, waterpump etc.). The only minuses where that the passenger's window didn't move up or down and the driver's seatback was stuck (but in a comfortable position

). And all that for $3200.
Why am I telling you this? Well, because another guy came 5 minutes earlier and bought the car. :'(
So now I'm back to the other 325is I mentioned before (the one with 90k miles). Made an offer for $2500. Owner said $2900, but I'm reluctant to buy, because 300 bucks would by far not be enough to transform this car into the same condition as the other one. I mean, just the windshield is $200. And mind you this has a few dents, plus the leather is kinda bad at some places. The moon roof is jammed too, only open halfway and then gets stuck.
So the only advantage is low mileage, but would you pay that much for it?