I need to help raise $90.000 for a Marching Band Charity?

You could try a silent auction, those seem to bring in some money. We did this in my music program last year and they raised a ton of money, and my current school does this every year, a gala with a silent auction. Ask all the kids if their parents can donate any services that people would pay for, or to go out to businesses and ask for a small donation of service or items for an auction.