There's the occasional hipster/art noise show but not much for real power electronics. I'm in San Diego, as well as Mr. Unit 731. Might be a few shows in the area in 2013, in the summer...
As for record stores, there are a few that carry the more popular artists (Throbbing Gristle, Prurient, etc.) but you'll have a better selection at Vacation Vinyl, which is up in the LA area.