I got the "dual" seat which usually goes for $399. Because of the very large size of the seat, the F6B seat is an extra $125 for a total of $524. I believe that the solo version would be $444.
Rick installed the new Utopia backrest which I brought with me. He recovered both the Utopia backrest and the passenger backrest (front facing surfaces) to match the basketweave pattern used on the seat. The charges were $45 for the passenger backrest and $85 for the Utopia (recover and install).
Side note: My Utopia backrest is the extra cost, quick remove version so that I can remove it if I don't care to have it mounted for short, local, running around trips.