Yeah tis a weird one.
Sometimes I quote £40-£60 and I get a look of shock and "oh, I'll have to think about that, can I get back to you, other times I quote a couple of hundred quid if it's a big job and they are fine.
I find the worst customers can be my existing window customers who have never had a gutter clean before, I think they expect it to be comparable to the price for the windows.