Funny that, I just rang a friend of mine today asking the same question, then saw this thread. Said friend knows a bit about these things, and said he will email one of his contacts at BMW Motorsport to ask him, although he added that he was pretty sure they did not keep good records of these. BMW Motorsport did not "build" any cars as such, they sold "kits" that the owner or team would nail together, or at least that is my understanding of it. Most information suggests they sold over 300 of these kits, which is a lot by any race car standards. The "works" cars could have been a built by a number of teams, Schnitzer, Zakspeed, Linder and Bigazzi being the most well know, and Tony Longhurst being well supported down under.As far as I know, no-one has formed a register for original motorsport M3's (built from BMW kits)- could be something to look into perhaps. I will let you know the response.
Bullett- I think that is called thread hijacking! Anyway, there were a few on racecarsdirect.com lately, looked like good spec. too. Also one in Australia a few months ago, still for sale I think, but is a "works" shell that has been built back into a car. Look at the pics, you will understand. Not cheap cars to buy anymore.
http://www.racecarsonly.co.uk/classifieds/T
etails/I:3aec345a-1560-5a05-120f-2ea1cfc1cf35/index.htm