A regular e12 commands 5% more than an e28, judging 528i cars so about $22k
Of the Motorsport 5 series, in order of value:
e28 M5 $105k
e12 M535i $50k
e39 M5 $40k
e34 M5 $35k
e28 M535i $28k
e9s are worth a lot, 6 series not so much, not even the M88 M635CSi. This is Europe and after all they are European cars.
