Some programs of not for profit, and the cost of "renting" a field needs to be covered.
What in goodness sakes does "not for profit" corporate status have to do with properly budgeting costs needed for a full fiscal year? "Not for profit" does NOT mean that employees are not making money on the process and it similarly does NOT mean that operating capital cannot be retained at a reasonable level between IRS tax seasons.
Your argument is "we are not-for-profit, we have no money in the bank, we cannot afford to rent a field to run a tryout, so we need those interested to kick-in to help support our business".
We would argue that if you do not have the funds in the bank to maintain operations, let's let free market prevail and have those players go to a sustainable club. Get the point? Tryouts should not be fund raisers, scholarship pool-building vehicles, or revenue boosters - they are tryouts, nothing more.
