Common problems on these car sinclude rear shock mounts(upgrade to E46 Cabrio mounts or Z3's), power window failures, premature wearing seats, radiators(necks) go at 100k, as well as clutch fans.. early build cars had plastic impellar water pumps which failed---> simple upgrade to later metal version is required, early build 95 cars also suffered from faulty valve retainers which reaked havoc on your head if not upgraded $$$.
Umm. lets see all rubber items will need to be changed out on older cars (bushings and such), driveshaft guibos(flex disc) are a common wear point also. Expect to spend some money installing new brakes and maybe a new clutch. I'd also watch out for 96 and up cars with the digital climate control, they sometimes fail (95's had more precise analog controls). I'd also watch for cars where the owners are selling too cheap.. most times these cars have some history you want no part of... That's all I can think of now, it's gettin late..

later on