first of all you need the licence i paid £250 inc vat
then theres the cost of hiring in a machine we pay £400+ vat for a weeks hire self drive
before you can hire one you will need to check your insurance covers you for using a cherry picker as its a plant vehicle
you will also need to prove you have got adequate insurance for the machine before they will hire it to you
some hire companies will let you pay a bit more to cover the insurance for the machine.
Alternativley you could hire a machine with a driver but I know its not cheap
As to pricing the job itself i wouldnt like to say unless i saw the job ie access,health and safety issues with pressure washing at height, is it on a new build site or on a residential site,what if any chemicals do you need,whats the risk of getting other people wet etc,etc
Hope this helps