There is a groupon out right now for a photo-booth. It's $399 for 3 hour photo-booth rental or $429 for a 4 hour photo-booth rental. I didn't have a photo-booth at my wedding so I have NO idea if those are good prices or not, but I just thought I'd pass on the information. Groupon and Living Social also often have good deals for things you can use related to your wedding (ex: Vistaprint, photo books, canvases, etc) so it's always good to look and see if they have any good deals!
Happy wedding planning!