While not necessarily for ///M cars, keep track of what goes on at Infineon Raceway, as it is a stone's throw away from SF. There are plenty of schools there and various events, I myself did a 2-day RS 4/R8 Performance Driving School back in 2008. Incidentally, there was a BMW Alpina event the second day and we drove alongside Z8 Alpinas (and B7s) and Alpina's owner (Andy Bovensiepen - the son of Burkard, founder of Alpina) very own track prepped E30 M3, which slaughtered even GT3 Porsches believe it or not (Andy is a pro). Still have pics somewhere of that beast.
There is also a race school there that works year round, and you can start off on lower classes of cars before moving to open wheel (I believe they have Miatas, so that's a good way to start exploring RWD capabilities on a much less powerful, albeit lighter car).
Kuddos to you for wanting to spend your first "mod" dollars on improving yourself!
2011 BMW E82 1///M: AW, all options; Renntech, Akrapovic, Forge, P3, RevoZ CF bits, many mods
1988 BMW E30 M3: Hennarot, S14, stock
2016 Porsche 981 GT4: Guards Red, LWBS, SC, full leather
1998 Porsche 993 C4S: Zenith Blue, last aircooled widebody, Bilstein PSS10, Fister II + Fabspeed exhaust
2008 Audi B7 RS 4: Sprint Blue, Audi Exclusive Euro Bucket Interior, Premium+Titanium, many mods