[Jon Stratis]

Many vendors allow customers to create an Open Purchase Order. Basically, that would let the school authorize a certain amount at the vendor, and then the team can spend it freely. So you could set that up now, then order what you want when you need it during the build season.

On my team, mentors pay for everything using credit cards, and then submit receipts to the school for reimbursement. So long as there's a clear understanding about spending limits, this method really poses no problems. You just have to convince the school to allow it!