How much should a volunteer coach be paying for out of their own pocket?

If the team only functions because the coach quietly buys the missing equipment, the system is not really working. I’d list the things you are repeatedly paying for — balls, bibs, cones, pumps, replacement kit — and turn those into a small agreed team budget rather than lots of invisible personal spending. Give one person responsibility for equipment and one clear route for expenses. The coaching staff should know what they can buy, what needs approval and who replaces damaged items. More volunteers should reduce the load, not create more jobs for the lead coach. Nobody needs a complicated finance process for a bag of cones, but there should be a point where “I’ll just pay for it” stops being the default solution.