I really want a photobooth at our wedding. Like, really really want one. We have already decided that I will most likely be asking a friend to shoot the wedding, so that should cut down on the actual photography costs. Hopefully we can fit it into the budget, or do one DIY. Most include 2 strips of each sitting so you can set up a scrapbook station which could also serve as a guestbook!
Red Eye Photo Booths ($675/4 hrs, $30/hr for idle time but set up one hour early free, only print one strip, unless you pay extra)
NE Photo Booth ($1000/3 hrs)
Creative Photo Booth Rental Wicked Fun Photo Booths (not sure if they go to RI)
Some DIY Photobooth articles...
Offbeat Bride (detailed tutorial)
Mason Jar BrideInstructables