Based on the contracts that I know about, there isn't an out front payment, so to speak. There may be a few hundred dollars in advance of contractual compliance, but there's a schedule of payments based on performance of duties associated with it. There are too many possibilities that can happen, which would give the donor pause to pay more than that.
In one, that I know of, even school grades come into the mix. You're either maintaining eligibility, or you don't get money. You either perform certain functions, or you don't get money. You attend practices, and all required attendances as applied by the school/program, or you don't get money. Get arrested for any reason, and you don't get money. Each can even include termination of the agreement between the donors and the student.
The higher priced deals are usually nationally realized deals with companies like AT&T, Nike, or any variety of donors. They are for the most part one year deals, that have a donor option clause to continue them in each successive year, at their choice. Once again, "good cause" dismissal from the deal is included to favor the donors getting what they will pay for.
Any donors who guarantee money out front are pretty much idiots, or liars. The kid's agent is also a buffoon. He should have known better.