I purchased one for our Sunseeker/Chevy not long ago from Shop4Seats. Rather than the entire base, the one I have sandwiches between the seat and the factory base. This will raise the seat about an inch and 5/8ths, and will shift the seat to the left by a couple of inches.
This was $228 delivered. I've received the base but have yet to install it. I started a new thread in the Sunseeker forum regarding this mod and will update it once I've completed the installation.
Formerly: 2000 Four Winds 26Q/Ford, '96 Kit Sportsmaster 22' 5th wheel, '91 Sunlite truck camper, Wildernest flip-top canopy