yea does it run?
My 89' 735I was sitting for a little bit when I got it. I gave it some extra love and it's running great now. I did engine flush and two oil changes. I think I did them about 1,000 apart, no real reason just cheap preventative maintenance. A by-pass oil filter might not be a bad idea. Amsoil makes one that filters out particles as small as 1/10 of a micron. I plan on getting one soon, especially because I'm upgrading my air intake to a not a safe as stock system.
Things that were worn on mine:
Control arm
brushings
hoses
shocks -functional but not BMW like ride
O2 sensor will need changing soon. Your owners manual tells you the intervals. I think it's every 50k miles or maybe 80k I forget.
TRANSMISSION-check that fluid. If you drain, which I would but that's my opinion, look for sludge in the pan. If so you might have some problems. If it's still good (silky smooth shifts) baby it, love it, care for it like you own child. People always seemed to neglect their transmission. I've heard people telling other people that the fluid is for life, just top it off. If you want it to fail at 160k sure. I treat mine like my engine. It gets regular oil changes only not as often because there are no combustion by-products. Once I'm done with the initial flushes I will change out twice a year. But I drive across country a lot. Good rule: check it every time you check your engine oil, which I hope is weekly. If it's not red and translucent, flush it.
My car is coming back to life with just products I get from the store. It rides as good as any of the 97' GM cars I test drove.
Do the little and cheap fixes first before paying some grease monkey. Unless they've worked on a BMW before, chances are they're scared of it. I took mine in for the trans oil change (free due to advertising TV airtime trade-offs with my employer) and they had no clue what to do with it at first. I had to walk them through it. I don't waste my time anymore. The only difference between them and me is they have tools and a lift. I have the power of these forums and people like jeffreyb4me to tell you exactly what's wrong just by listing the symptoms.
Regardless of what people tell you, they are just as "easy" to work on as most other cars. And, parts I think are more plentiful (bavarian autosport, BMP design, etc) and there is such a huge following. There just seems to be a shortage of competent people in my area, even though there's a dealership in town. But that's what I get for moving to Arkansas.
Find someone who knows the cars and have them take a look and drive it to assess need/want list.
Remember: Fluids and filters first.