you should price by meter, take in to consideration if they have soffit boards, have chok-a-blok the insides are do the want a extra flush, are you just cleaning the out side only. do they have barge boards.
i split my gutter care in to 3 grades
Bronze
Outside of Gutter and Fascia cleaned only / Inside of Gutter cleared only.
Silver
Outside of Gutter, Fascia and Soffit Boards cleaned and Inside of Gutter cleared.
Gold
Outside of Gutter, Fascia and Soffit Boards cleaned and Insides of Gutter cleared, finally 'Brushed & Flushed'.
soffit boards and miscelanius upvc is priced sepretly.
i find on average upvc cleaning costs 8-10x the price of the window clean.