If, like me, you're planning on being on the Wind River Reservation for it, don't worry too much about the permit you supposedly need. The town of Pavillion is charging five bucks for parking, but that's literally the only thing I can find anywhere that mentions any cost at all. This site, which is linked to by the city of Riverton, seems pretty official, and doesn't mention permits of any sort (...guess we'll see on eclipse day!):
http://www.windrivereclipse.org/