When I was growing up, my mom used (new) plastic shower caps in lieu of Saran Wrap. It was a cheaper option and, although they weren't that good looking, could be used over and over again. I've never gone the shower cap route myself, but I really love this tutorial by Allyson Hill for Evo Travel Lids. Basically, it is the same concept, only better looking. I think I might make myself a few.
See the full tutorial here.