Rob,
I bet you don't get many responses from your leaflet with £9 on. It's only £2 difference!!! That won't even buy you a pint.
Take a leaf out of the more expensive window cleaner's book; remember you've got to be able to cover holidays, time off due to inclement weather, business running costs, the tax man, sickness... and probably other stuff.
But as I say, I bet you don't get much of a response.