As a current parent covering the costs of a World class member, here's a short summary of where the majority of tuition $$ goes from my perspective (my 2 cents 😉 ). Not in any particular order.
1. Instruments - New ones every other year ish
2. Uniforms
3. Food
3. Transportation
4. Staff
6. Housing during camps and tour. I don't think those high schools are free.
7. Equipment maintenance (Trucks, trailers, instruments)
8. Props
9. Maybe some music licensing?