depends where you are generally down south its more not so really cos things are more expensive but cos there isnt a window cleaning culture like there is up north or where you are,
if we had 25 in a row down here im sure everyones price would drop but its very rare here to have £20 houses 15 all in a row all individual customers up north its normal and you have much less managing,
all round small houses £12s
bit bigger £15s
bigger depending £20 etc etc.
i tend to stay min £10 fronts but i do go down provided customer has cheque book or online to £8 , will take £6 and i think i have one for a Fiver takes 20 secs thou

end of the day its not so much about the minium price per unit its the time you can clean it in and get paid.
i dont see whats wrong with cleaning one window for a quid if the customer is always there and you dont need to move your van!