I charge more than any of the amounts I've seen above and I'm constantly busy. There are a bunch of contractors in my area that charge more than me. I know this because I have seen their quotes. And they are busy. I once spoke with a Mr. Sparky tech and he told me they set their pricing at 30% higher than highest priced electricians in the market, and they are busy.
@Jerramundi is framing the debate like it's immoral or illegal to charge a higher rate than some people are willing to pay. This is just not true. As long as your potential client is fully aware of your price or rate ahead of doing the job, you are doing nothing wrong. It's up to the potential client to compare price, experience, licensing, insurance, reviews, and all other due diligence factors to select the contractor that best fits their needs. Upon hearing your price, some (or many) potential clients will say "no, you are too expensive". That's OK. You only want to work for the people who are willing to pay what you ask for.
From a pure economics stand point, a one-man-show contractor should charge as much as the market will bear because they are selling a limited resource, their labor hours. Your minimum charge must be the sum of all your operating costs plus a profit amount divided by the number hours you can bill. If you can't get that, you can't stay in business. But there is no maximum charge.
Economic theory says if you are not getting enough clients, you can lower your price, but you can also look for more clients (or different clients) and keep your price the same. And if you are getting more clients than you can service, you should raise your price and continue raising your price until you are no longer filling your schedule with jobs.