I always say this, and it's worth mentioning again: don't get freaked out by all the stuff people talk about on the forum boards. It's human nature that people complain more than they give praise. There's a reason why the E36 consistently made Car & Driver's top 10 list through the '90's. They do have their share of problems, but I really don't think it's any worse than your average car of the same age. A lot of guys are replacing this and that all the time because they're getting up in the mileage, and naturally the car's gonna need some things.
If you haven't seen my writeup yet, take a look at it:
If you wanna avoid the cooling system problems, go for a mid '97 production date or newer. Even if not, it isn't difficult to deal with anyway . . take care of it once you get the car, and you're good to go. If you can't afford an M3, the 328 is a good alternative; they're gonna be more reliable than the 325's that started the E36 lineup.
But you might also consider an E30 . . great car you can beat to sh**, and it'll still kick you in the a** right back