You most likely can locate a E36 in good condition, particularly if it is a "track" car and not a daily driver. Age of the car means nothing if it is a built for track machine. If it is to be used also for a daily driver, then that is something else.
Now, a GTR, can get a sand paper face quicker than a E90, so I would not recommend one of these. You have to be a wild thing to drive it for one, and two, have only one eye and half sense to pay that kind of money to put it on the track.....
However, one H of a car but who would want to podium at a BMW event driving one of these......(me)
vz