Pay now or pay later is the answer
Its not about clamping force but about servicing and wearing out the threads on the block and having to repair them. If he cant afford the price difference, maybe he should not be running a Sprint class anyway.
When I ran 410 Sprints, I would sell my RR tire that I ran the previous week for $40/$50 to a rookie to save THEM money ($200 new) and BUY my fuel for the night