In the summer of 1996 I saw a red ///M5 pull next to my 1992 Jetta at a red light and then blow thru the intersection and up a steep hill before I got out of 2nd gear (wow!!!) I gotta' have that car, I thought. My decision was confirmed after driving my friends '92 535i and simultaneously blowing the doors off another friends '93 300zx on a road trip between San Fransico and L.A. (the owner was asleep in the passenger seat which lessened my inhibition to do 115mph, which seemed like 75mph)
For approx. 5 years I searched for an ///M5. A clean, well cared for ///M5. 3 years ago I found (3) 1991 M5's and a 1995 540i w/the ///M package in 1 week for sale. I took my time and looked over each car thorouhgly. I chosed a silver with black int 1991 M5 which had been owned by a gentleman who owned another M5, an M3, and a Carrera S4. This M5 only had a little over 84,000 miles and, except for typical oxidation of silver paint caused by So Cal sun, was in excellent condition.
When I bought the car the owner handed me a binder which had records of everything he had done to the car. The binder had everything from copies of 2 articles specifically written about the e34 M5 from the L.A. Times newspaper & European Car Mag to the mileage every time gas was purchased to receipts of aftermarket parts purchased and everything else done to the car. Since owning the car I've been doing preventative work to insure this baby last another 10-15 years.
This is all to say, do your due diligence and take your time when buying ANY car. My case may or may not be a unique case but understand, buying a used car has more to do with the previous owner(s) responsiveness and care than it does the car's reliability. Eventhough the majority of BMW owners I've meet treat there cars like offspring and not just another thing the garage, I've driven some e34s that needed to be put out of their misery.
So, continue your research -- drive as many as you can -- don't rush in -- inspect, inspect, inspect -- and for goodness sakes man! have FUN on your quest to becoming a "BIMMER-HEAD" (this message was brought to you by the Long-Winded-Out-of-Work Film Directors Assoc.[L.W.O.W.F.D.A.])