Hi,
As for price its generally down to how long you think it will take and what your prepared to do it for. For me i generally charge around the £30 - £ 40 mark ( i live in the south of the country)as i am happy with this and i find it generally takes me an hour or so, I guess it also depends where abouts in the country you live in to what you can charge. I use a seperate pole and brush for cons roofs tho a cheap harris pole ( £15 from B&Q) and a vikan flocked sill brush as i find the flocked brush with lots of bristtles is a bit better for cleaning the finalis (not sure spelt right, The decrotive bits on the top of the roof as they can be a bit flimsy).
Paul