if you do go this way tosh
go to a sign writters and ask about a deal, if they include there logo etc you will get a few quid off
I've considered this, but I was thinking of making them myself.
I've got the skill and patience to make a good template, and then spray paint my sign onto some stiff card or board.
Apparantly these signs only have a life-expectancy of around 6 to 8 days before the weather/council/vandals/OTHER WINDOW CLEANERS get to them.
Off the top of my head, I can think of three good stategic places to stick them.
Just something simple (like myself) saying, 'Do you want a window cleaner? Phone XXXXXXXX).
As it is I'm getting 'nabbed' by people when I'm out shopping who say 'I've been looking for you for ages' (even though I'm in the phone books), so I think it's worth a go.