Just in case nobody mentioned it already, never pay in advance for any flying, unless you are fully willing to write off that money. Schools - often apparently very healthy ones - go out of business with monotonous regularity. People have lost a LOT of money.
Basically, just pay as you go, even if apparently that is more expensive.
Yes, fine, paying for the day, or if you're staying on their property the week is probably sound. More than that - just don't.
G