My school did a 10% "bonus" if you put money on account and it was in the form of cash/check. You can withdraw it anytime if you want, but you'll lose that 10% then. So if I gave them a $1,000 check they put $1,100 on account. That account is for dual (and was for rental) and I have another account for airplane which gives me a good fuel discount ($.30/gal I think?). Not nearly as good as the 10%, but I know 100LL profit margins are nill.
Be very careful with this. Ask yourself hard money questions about these things:
What do they stand to gain from having your $1000 in their pocket for X amount of time?
At today's interest rates it certainly isn't making them money.
Do they have a large number of students who don't have the discipline to keep showing up, if they don't give them a mechanism to find an account ahead of time?
Are the majority of their students young and relatively broke?
Do they dangle the carrot that they'll hire these same students they didn't trust with their own money, as instructors?
Do they value penalizing students who show up regularly, sign checks every week, and fly like clockwork? (This is the message they're sending, to me. Adults pay for services rendered at the completion of service. Pre-pay discounts send the wrong message. Students who don't fly enough will pay plenty when they need more hours to retain what they've learned and forgotten.)
Are there maintenance or other bills they were falling behind on that required a mass infusion of cash, and they spent it already? Any new engines hanging on any of the fleet? New hangar door? Signs that they needed fast cash and you were their payday loan shark?
Ask questions. Hard ones.
Numerous people have and will again, wake up to find the flight school doors locked, with a sign on the door that they're closed permanently, and their "account" is gone. Get in line at the bankruptcy Court.
Pre-pay discounts in aviation are almost always a sign of being on the ragged edge of insolvency.
When they're not, it's an insulting business practice to folks who normally pay upon receipt of services or goods, since we've all seen the bankrupt flight school drama play out before, locally, and the bigger ones in the national aviation press.
The other question to ask yourself is...
Is it worth risking $1000 of your liquid cash in an investment that can return zero, for less than an hour of flight time?