I would say you made only one mistake in this... the thread title.
Your question is an excellent one... (still a subject covered before, but none the less, a good question.)
If you were to ask me, I would say to buy a plain old miata and run the grand valley miata enduro.
That's a cheap race that gives big on prizes.
If you're looking for something a bit more exciting, and you want to stay in the road car realm, then go buy an rgt and run any of the races.
If you want to go race car, you may have some trouble since there aren't many racers for under 500,000.
However, the rally race cars would be an excellent starting point for a race car in that price range.
My suggestions though...
miata
rgt
rally car
Buy any of those three and run some enduros, regardless of which one, you should have some fun with it.
Good luck and have fun now that you're back.
Later.
