Biggest tip -- make sure the focus of the display case is on the "results" of your fundraiser (what are you raising funds for?) as opposed to the stuff you are selling.
Pictures of the new playground. Images of kids on filed trips or watching their first play. Photos from your fun nights. That kind of stuff... along with "thanks for helping us make all this great stuff happen" kind of messaging.
I am doing our annual fundraiser for our school this year. We are doing catalog sales with some food, and misc gift items. I need to put together a display case for parents and kids to look at. Any one ever done one and have any ideas to "spice" it up?