cameron,
I race in the Az region.
I used to race SM with SCCA. the SM class is not really a cheap route to go racing if you want to be up front. the pro motors being expensive, as expensive as my formula ford motor to rebuild(~$7-8K).
I sold the SM to get into formula fords, but that got a bit pricey as well since the same deal, you need a pro built motor to run up front, and it needed to be rebuilt every ~40 running hours.
I now am racing spec 944. it was a great choice, the people, as said before, are fantastic, and the car feels very safe(as big dog said earlier, get a good seat, and HANS) and robust, yet is fun to drive on the track.
the cars are not expensive to buy already built.
the most appealing thing to me about the class is the availablity of parts. I picked up a complete running and registered street car for $1500 to disassemble and will have spare............everything.
it has a good running motor , a working gearbox, and all the body parts/suspension, everything...........$1,500.
In AZ it the largest class in NASA, as well as SCCA.
was really a no brainer of a class choice.