Yeah, I have paid £85 for Mark Hamill too and think as a one off this is ok.
I only want Ford on my Star Wars poster now so I would pay what it takes for this.
Someone raised a good point about the price of Carrie Fisher compaired to Mark Hamill. Another example I would give is Roger Moore turned up at a recent event and signed for three hours for nothing. Yes he was doing a book tour but he signed my poster etc.
For me if you are going to charge top price then they need to be a first for the signing event, do dedications and be a genuine A lister