I have 95 850 GLT w/ over 120K miles- the car is great - VERY comfortable seats, sound system is great 9 (I installed a cd player when bought it 4 years ago), the 5 cylinder engine in my non-turbo model gives enough power in the city and on the highway.
There were a few problems w/ 850s:
1.many have evaporator leaking - when I bought the car i had to re-charge the AC system, but now it works fine
2. some had transmissions replaced - most likely because of mis-diagnosis-those cars had PNP switch problems or a solenoid problem which do not require transmission change, or because those owners were ripped off by unqualified mechanics.
3 there were miscelanious issues w/ seat heaters (broken wire), seat back cable.

I own the car since February 1999, and had to replace following:
ABS pump $400 (got part from a junk yard)
radiator $400
Motor mount$140
Ball joint $150
Fuel level sensor$200
All prices include labor and parts -done not at dealership.
I also change oil every 2500 miles, and do tranny flash every 10-12 months.
Brakes done as needed, and t-belt done once ($300)

Keep in mind that I do ONLY city driving - Ilive in NYC, and drive mostly in the areas, where you have to stop almost every block - the worst driving conditions possible. I put almost 60K miles on the car since I bought it.

Hope it helps. Good luck, Yuri