Not me, I just look at the job, think of a price then quote it. If it's a 50 foot job then you have to think what alternative means there are of clearing it. Provided no-one else in your area uses a guttervac then you stand a very good chance of landing a good deal. If it's a normal domestic job then you have to realise your competition might be a guy up a ladder. I look at the customer, look at the area and try to work out a fair price. Some guys think that because they have spent a couple of grand on a system then they can charge the earth.
I'm not so sure.