Yep, that's a good deal for sure. Unless you've made a seat, it's hard to appreciate what goes into it.
I can't tell you how many times people have asked me to repair a car or truck seat and expected it would be like a 20 dollar bill. I have one story where the guy had a full size truck bench and he just needed the edge where he slid in and out repaired because of the tears. He asked me if I could use the back of the seat since the material was the same but only a piece of it. I explained the amount of time it would take me to remove the bench cover as well as the back rest so I could get the piece and replace that spot and he just couldn't understand even then. Upholstery is just one of those time intense things that there is a lot of detail work.
Nice seat though and I'm sure the purchaser will enjoy it.