The school my kids attended in Alabama did this and it worked very well. The school was also K-12th grade. It works like a silent auction. Each class "room mom" was given a theme..like bar b q, chocolate, hawiian, Disney, restaurant certs., perfume, baby basket and etc. The students in each class would bring items to place in their class basket. Some of these baskets were really huge! Give about 2 weeks to collect the items and during the two weeks, hype up the sale of these baskets. Set a date and time, (try for a time after school but during a sports game at the school. lots of people to bid on the baskets). We had 15 baskets to auction off and some went for several hundred dollars.
We wrapped the baskets in pretty paper and lots of pretty color ribbons. Some of the baskets themselves were to big to wrap. I cant remember the exact amount raised but itwas somewhere around $2,500. and exceeded our expectations.
Good Luck!
Southern4sure