I've only done the one at EPCOT. Didn't want to but had let DH chose all the activities for one day Only One! Anyway I went in reluctantly and LOVED it. I'd do it again in a heartbeat. Would like to do the Ft Wilderness one too as it's an "off road" experience. According to AllEars.net the EPCOT tour is $95
You can also test drive them in innoventions for free. I think you only get to ride it for 3 minutes or so. But then you can determine if spending the money to ride one longer is worth it to you.