The seller (tech/designer/etc.) will charge what the buyer is willing to pay.

If enough people refuse to pay what they are charging, then the price will eventually come down.

It is possible because: 1. the boosters raise enough money to pay for it, and/or 2. since the band budget, as part of the district budget, has to be approved by the school board, the district green lit the budget and the money is there to be spent.