Hi Wayne
My $0.02 worth on the topic:
I would not even begin to value a BBS apart from basing it on future value of expected revenue streams.
My main comment comes from being both a (long-time) BMW owner and a (newbie) Porsche owner, and the differences that I can perceive in the use/maintenance of these cars. I have owned or currently own an E30, 2x E36 and E39 BMW's. Most of these started out new, and had warranties or maintenance plans taking care of servicing needs for extended distances (up to 100000 km or 60000 miles for the metrically challenged). BTW, it is being said that the US is metricing inch by inch.
It was therefore never required of me to actually get my hands dirty with these cars, apart from compulsive oil level checks, tyre pressures and such complicated tasks. One exception was the E30 325i, that I bought used without a maintenance plan. I am therefore of the opinion that the majority of BMW BBS visitors with new model cars do so for technical advice to evaluate or diagnose some issues, but would leave the maintenance or repairs to the agents since these would mostly be covered by the maintenance plan or warranty. So I would guess that the only real business opportunity (parts sales) would lie with the owners of older models who would do their own repairs or modify them for track use, and there may well be a fair number of them. The correllation with the Porsche BBS will be if you can distinguish BBS visitors and/or parts sales between older 911/944/928 owners and 993/996 owners?
So you can understand why I had to get a car that I can actually tinker with, and I am having great fun learning with my SC!
I wish you good luck with thinking about these issues before offering someone cold hard cash for his BBS, and I look forward to the 101 projects book for the E36!
LeRoux