Good idea! I know personally our school takes in all the profits from parking - and they definitly don't spend it on upkeep!
If you can con yours into giving you the profits, it sounds like you definitly have a good fundraiser for you. How big is your high school? Mine only has 800 students and only enough room for parking the seniors. Other schools in the area though have 2000+ kids with tons of room for parking.
~Tom~, who's friend had to pay 100 bucks to park at her school.