Earlier the better. The good deals don't last long. Sometimes you can buy the stuff as the guys are unloading their cars! Less they have to carry in!! There will be an auction @ 1300 (1PM). Super sweet deals at the auction. If you want to go giant scale, this would be the time. I've seen 1/4 scale 1k planes go for 300 - 500.00. Having said that, the more money you can bring the better the deals.
At one of the last swap meets, a Lady was selling 25cc - 100cc enignes for 10.00 a piece!!! They had belonged to her desceased husband and one of his wishes was that see sell them cheap so others could enjoy his once beloved hobby.
Be ready to deal with the guys. offer bottom dollar and wait if they refuse. Prices usually come down near the end of the show.