Is It really in Pristine condition?
Does it truly run as well as it looks, how is the front suspension, rack and pinion, tie rod ends, does he have receipts for this work being done? My 1988 325is has about 260,000 miles and I have replaced the rack and pinion and tie rod ends since buying it, I am now having the drive shaft redone, all of this due to wear from mileage. They are wonderful fun cars, but parts still wear out, I bought mine for $1100, so It is worth putting more money into mechanically.
Look at what you are paying upfront and what it will cost you to do the required maintenance and decide if it is worth it to you! For me yes, I drive my car hard and pay the price in wear and tear. But, it is designed to eb driven aggressively or it would have been a 325e. It may have been babied, but if you are really going to drive it and these items and more have not be redone, plan on doing it before to long.
Can you post any pictures, what color is it? Manual or Automatic, what color interior?
Wish you the best, i would buy another twenty year old one again!