Heh, my GF had one for two years and I also got it back on the road after a semi-write off, so I know quite a bit
Make sure you get a UK car, plenty of japs about. The 1.8 V6 is pretty fun, felt quite nice to me and sounds good too. I'm going to say a fair few negative things but I really liked the car. It was cheap, powerful, handled well and had some gadgets, it was also slightly rare, a lot of people didn't know what it was. You could throw it about and it would never bite you. Insurance was very cheap, she was 18 and it was ~£1000 (the reason we bought it)
It didn't break down once in 20,000, we had a dead battery but that was it.
Problems we had on a 92 car with 90,000 :-
Noisey hydraulic tappets, I tired everything bar replacing them but the best I could do was quieten them for 4000-5000 miles.
Sticky calipers
Slight thirst for oil
Awful MPG, I think it may of had a failed o2 sensor or something. We never got more than 24 mpg regularly, when I drove it for a week it did 19. On the motorway you could scrape 26-28 and that is with her driving. Small fuel tank afaik, 40 something litres which means it only did 220 miles before empty.
She had an accident at the rear which I tired to put right as cheap as poss. First problem was that it was hard to find scrap yard parts (this is two years ago, maybe easier now), I did manage to cover most bits but some I had to go to the dealer for.
The dealer prices are jaw dropping, they were more expensive than BMW main dealer. They wanted in the region of £80 for a washer bottle, a rear caliper was £249.
Sadly I never could make it driver perfect after the bump, despite a proper 4 wheel alignment something else must have been still bent. Then a year later she got t-boned and it was writen off - poor car
In short, buy one that is in good nick and you should be fine. Generic parts like fliters/plugs/pads/discs were all cheap enough and available in most cheap parts shops.