As an old plumber I always used to tell the helpless, hapless, weak, mechanically deficient, ability deprived rich folk that I would only CHARGE THEM GOLD BOOK PRICES for a Home Depot 2.00 fix because I am such a nice guy.
2.00 dollars at home depot (parts not including contractor discount), I would charge them 68.00 dollars + 100.00 (service call) + minimum 2 hour at 55.00 dollars per hour.
So 278.00 dollars for about a 15 minute job, it was my knowledge and experience they were paying for.
One of the things that REALLY gets my back up is when one of the "Learned Class" cops the "I'm smart and I know that you're trying to cheat me, tradespeasant" attitude.
I won't work for them any more after that.
I usually have them by ten or fifteen IQ points, and I have to listen to that Mitt...
Morlocks Rule.