Redline is probably the best way to go....like you said its not going to be any cheap than redline, unless you get a fund raiser going...even then you may only shave 30-50 bucks per person (comes up to 170-200 dollars out of our pockets).
And they supply all the flag men, instructors and safety personel.
They do it in groups....its 3 groups total. A beginner class, intermidiate and advance.
Each gets 15 minutes (half hour, i dont remember) on the track and then they rotate to the next group...and its like that all day from 7am to 5pm when they close up.
Lupe