I refuse to talk about the 951.
'92 525iT
Bought for $1200
Invested: ~$4000
Currently Own
'91 M5
Bought for $500
Parted $2000 worth of parts
Kept another $3000 worth of parts
$4500 ahead
'89 525i
Bought for $900
Found bent frame and spun rod bearing a few days later
Made $200 on the car.