Children look up to their principals and other administrative personnel in the school. They see those people as having special jobs and being important. Auction off a chance to spend part of the day with one of these special people. The student could win a chance to be the principal for half a day and eat a special lunch in the office with the principal. The student could also win a chance to help the office secretary in the morning when things are busy.
Student artwork is a big seller at school auctions. A hand painted chess or checkers set would be an appealing gift for a family to bid on. This is an item that the entire family can enjoy. Have students paint the game pieces and glaze or lacquer them to ensure they last a long time. Blank tiles can be found at craft stores. Have each student decorate a tile and then frame a large mirror using the tiles. These kinds of items will require help and financial assistance from parents, but sell well at school auctions.
These big ticket items will require help from students' families, but will sell for hundreds of dollars at school auctions. For younger classes, purchase a raw, wooden, child-sized table and chairs set. Have the class paint and decorate the set. Varnish it when it is done to make sure it is durable. Students could also paint and decorate a bookshelf, end tables or even small shelving for the wall. These items are considered treasures by parents of the children who did the decorating and will sell quickly at school auctions.
Parent teacher organizations can ask community businesses to offer coupons and package deals to sell at the auction. See about getting birthday party discounts at children's entertainment establishments. If you live near a theme park, coupon books are always a big seller. Offer a package of local restaurant gift cards that have been donated. For a more day-to-day deal, auction up a front row parking space for the school year or by month. Parent's love these opportunities to help the school while making life more convenient.