Ask people to donate articles they no longer need to raise the money, and have an online bidding. You might what the favorite businesses in the different areas, amusement parks, theatre tickets, restaurants, etc. and then approach those business for donations of items or a small gift-card and include these in the auction, or sell raffle tickets for items. You might call local celebrities, like newscasters or sportcasters and see if they will donate a shadow ride-along with the celebrity experience that people can bid on, or local politicians would donate an hour to meet or have lunch with bidders. Try to tie in the learning theme to asking people to volunteer their time for your auction bids. Ask people to donate $1 to vote on the prom king, prom queen, and prom court. Sometimes hotels might give a discount, or limo services, or dinners, gift baskets, etc. You could use pay pal to sell raffle tickets and maybe have a link from your school page to an ebay site where people can do the bidding.
You could put together an online Prom Program book (similar to 'Playbill' or the programs at plays or sporting events), include the biographies of your prom king, queen, and prom court. Ask people and businesses to sign up to place ads or favorite photos in the Prom book. Charge for the amount of space needed - 1/10th page, 1/25 page, 1/2 page or fullpage ad.
Ask for volunteers to join your team.