[North Coast Cab]

Just go to the track and talk to some people. You'll find the best fit for your area.
Don;t forget helmet, suit, gloves, shoes, spares etc. will set you back a couple hundred to start, more if you go for a head/neck restraint.
4 cycles are much much easier to manage than the 2 cycle, plus you don't need a $200 starter.
My son and I do it just for fun, KT100 Can Karts, and have learned a lot the last few years.
Racing competitively is a whole other ballgame. Racers are serious, well funded, and committed to paractice all the time. I am amazed at the investment some people have in their rigs....biger than many at the PCA/NASA events.

Good luck!