Well I don't really know what your trying to do here. You can't just go to an auto auction and buy 6 cars and then fix em a bit and resell them. Sure it'll work at first, but eventually you will need to file for a dealer's liscence.
I used to work at an auto auction in high school and there are two different auctions. First are open auctions with donated cars (mostly rich people donating their beater in for tax deductions). Second are dealer auctions, dealer cars with minimum reserve to be sold to other with dealer liscence (cars they just want to get rid of).
If I were you, try it out and just simply do one car at a time for side money. I hope you're very good with cars, as they tend to "rig" the cars to run better through the lanes then they actually will. If you can pick out 90% of a car's issues from a simple test drive and 10 minute look-over, you'll be fine. Bring it home, get parts from junkyard. Fix the parts, detail the car, and put it up on craigslist. Could make around a grand profit a car if you do it right. Don't expect alot of newer cars though. Most things you find will be late 80's-mid 90's.