Take an office staff of 4 with salaries, taxes, and health insurance, you are at 250,000 maybe 300,000 not including the corps staff. Throw in stipends for the BOD (not all groups have volunteer Boards). Now add in rent or mortgage payments, utilities, insurance, travel expenses, etc., etc., your easily up well over 500K per year in operating expenses. I did not even include the six figure salary for the corps director.
Most World Class corps are now multi, multi million dollar operations.