I've bought plenty of cars from Copart auctions. Some great deals, some not so great. Generally if you win an auction, it's because you outbid the businesses that know what the cars are worth. If you know what you want and your labor is free you can come out ahead. Fees can add up quickly if you are not a 'business' buyer.
I have flipped a bunch of Hondas and Fords. The ones that were easy to sell were cheap family cars. I bought my flood car from Copart in Houston:
The Houston 04 SE
Bottom line, as a non-business you can often find better deals on Facebook/Craigslist, but if you want a specific car model that isn't easy to find locally, it can be a good source.
Edit: Learn your state's laws and regulations before you spend a significant amount of money. Oklahoma is pretty easy to deal with for titles, registration, and disposal. Some places can be a lot more difficult and expensive.