This is just my personal oppinion here, but i think a lot of you guys are seriously under-selling yourselves.
If the job was that easy then the home owner would do it themselves, If the husband was confident on ladders the same would apply. But their not, thats why you do it.
You offer a service, you risk your life and health to provide that service, you work in all weathers to provide that service.
Charge accordingly, don't think Oh i'm only a window cleaner.... you are a service provider.
The days of Old George pushing his bike along with ladders and bucket, charging next to nothing have gone forever. £25 - £30 per hour is what you want, if they won't pay that then they can do it themselves.
There you go, rant over
Denzle