If it were even possible to cap or limit budgets, more affluent Boosters will always step in to supplement whatever shortfalls exist--how could you regulate that?
And there are also the "Band Fees" for the "Competitive" ensemble charged to students who want to be in that group which is a part of the general marching band....or sometimes referred to as the "Outside Performance Ensemble"...... Research what those fees are assessed to each student.
A director can teach at the highest level of efficiency and effectiveness, but limited staff and resources can't compete with larger numbers in staffing and larger funding.