As someone who used to race weekly at the local NASCAR tracks, I vastly prefer Chumpcar racing at this point in my life. It's such a great atmosphere and the tracks they race are amazing.
If you really want to get involved, see about joining an existing team. Our team has prepared two cars for Chump and spent very close to $3500 on each one. We scored a lot of deals through racing buddies and had all of the tools already.
Car prep is huge. That's where you win the race. Don't just replace the beaks pads and call it good. Replace the brake lines, rotors, etc. Going through the car and addressing every part will ensure you finish. That's why joining an existing team is a good idea.
As far as gear goes, we had a rookie on our team this past race and he used
www.racesuitrental.com. He had a great experience with them and it was under $200 for everything needed.
I still recommend this racing to everyone I can. It's a blast and I'm super excited to run more races next year in the Chevette.