Originally Posted by cohenfive
in addition to looking here, don't forget to search on your local craigslist. the bay area is the home of cl and there is a huge amount of activity going on the site here...i've bought and sold several cars now using cl. in fact i usually have more luck with cl than anywhere else. you have to be careful but if you know what you are looking for it is usually listed on the bay area cl. i just did a quick check of cars for sale by owner and there are several really nice sounding e92 m3's for sale now...so good luck!
Welcome to SF! Just in time for the Superbowl.
P.S. If you actually will be living and working in the city, I'd suggest at least considering cars a bit smaller than the M3. Then again, if you loved having the M in London, you've probably already weighed the pros and cons. Either way, good luck.