Clean Cloth if you are happy with the price you charged then why worry what others would have done it for, if you're not happy then learn from it and charge more the next time, as for doing it cheaper than your original quote, I would say as a rule its better
to stick to your quote and be prepared to walk away if they dont agree to it ( it makes for a happier work life ) but this is a lot easier to do with plenty of work on your books.
I quoted 135 to clean his FSG and windows thinking I would be knocked down as everyone around here seems to like to haggle, so I go in high. If they do not knock me down it is a bonus.
He said and I quote "Oh, another window cleaner said he would do it for £100" I said "Ok, you had better go with him then as I cannot match it, all the best" Before I could hang up he said, "wait, I will speak to my business partner,,,,, wont you move at all on price", If I can do the windows at the same time as the FSG I will do it for £120."
It is a Bungalow, very near to my house, easy access and I got a regular 4 weekly clean out of it.
As you say, it is easier when you have plenty of work but I am prepared to leave the job if they wont pay a decent rate.
To answer your initial question, I am not worried about how much others charge but I am interested how much they charge. The more I ask the more I charge as I find out my competitors are pricing higher.
I was going to quote lower for the double garage but after the replies I got in this thread quoted higher and got it. Steep learning curve.