I'm a professional detailer, and I charge $150 for the works. I believe that that IS too much based solely on the information your giving. The deal with that is, sure, it would look new when he got through i'm sure, but there are other detailers out there that can do the exact same thing for half that price. And believe me, high speed buffers are a good thing IF AND ONLY IF the person using it knows what they're doing, many detailers use it as a way to fix paint imperfections, heavy swirling, etc. and go to a random orbital buffer to finish off the paint, and fix the imperfections the high speed buffer caused. It just comes down to experience, ask detailers to show you pictures of their previous details. Believe me, they have them, if they don't, don't trust them, becuase apparently they didn't do to good
Hope this helps, sorry for the long post!