We actively chase this type of work and price similar to Daz, a great way to pull these type of jobs is to scrub a section clean between clips on the front of the house, we then show the customer the cleaned section and tell them the price, even if you get a no on the day they always seem to come on board eventually, we do the same with conny roofs, scrub one panel clean, it's our version of " would you like fries with that"
Graham