Some of our most popular auction items each year are birthday parties hosted by the teachers. Usually those are actively bid on by kids who currently or previously had the teacher. There are 2 or 3 teachers' parties that are highly sought after because they are always so fun!
2 years ago we started doing a "reserved table" for a month for a 4th or 5th grader & up to 3 of their friends. One table is offered for each month remaining in the school year except December which is a short month. (Our auction is normally in October.) These don't go for a whole lot of money, but it's all profit because it doesn't cost anything to offer! The first year they only went for about $5 each, but last year went for more because the kids knew they were available. They didn't know they were going to be offered the first year.
The local bed & breakfast stays are also pretty popular.
A reserved parking space, 5th grade promotion front row seats, Principal for a Day, $5,000 worth of orthodontia (we have a very generous orthodontist that donates this every year), the teacher outings and the classroom crafts/baskets always go very well.
This is the second year that we are using Cmarket online auction. I know we are all looking for donations, but wanted to share what became our most popular items last year. Our younger classes made pottery pieces with their thumbprints which turned into frogs with unique faces and each one had their name on it. The bid were high and in several cases parents bid on these to give as a gift to the teacher. There were several other very clever pieces representing each child in a classroom.