kleen you made me laugh mate, thank you.
You said to be honest about your prices, well I think you are not far of the mark but you are going about pricing the wrong way, go and count the windows, pains etc.
I have one house I went to, and counted nearly 30 windows, and it wasn't a 27 bedroom house. The window at the front was a huge bay window, 20 pains to it. Now the cusotmer over the phone would have told me thats one window, which its is, but not every window should be priced the same, some take more work than others.
Personally I charge by the window, and each window by the pain, and also add in a call out charge. I do one church, which is an absolute pleasure to do, and I do it trad, every single little square pain, but I do enjoy it because, its worth the money I asked for, if I charged that like you do, I would have dropped it after the first clean.