Interesting to see everybodys comments on here and difference of opinion too!
I was just interested to see roughly what you full time experienced window cleaners are spending on average.   First thing i would say is that you need to be detailed with your expenditure and realistic to what you actually spend and don't miss anything out. 
Here is a breakdown of my plan of expenditure this year, or when i decide to upgrade my equipment and aim to go full time.
PLEASE NOTE - THIS ISN'T 100% ACCURATE JUST A ROUGH PLAN SO FAR.
Monthly/Yearly
Breakdown Cover   £12.50   £150
Internet + Phone   £40    £480
Printing Supplies   £5   £60
Van Insurance    £54    £650
Fuel     £80   £960
Moto Account   £12    £144
DVLA Vehicle Tax    £20    £240
Worldpay   £10   £120
WC Equipment*   £100   £1,200
Liability Insurance    £15   £180
Van Maintenance     £40   £480
Bank Loan  £185  £2,220
(Loan for £10k for van + System over 5 years, I Don't want a cheap setup)
Total   £566   £6,794
*WC Equipment is to cover Resin, Water Bill, IT, Trad Equipment and anything else Miscellaneaous.
Do you think this is too much or about average? 
Lastly, how much should i be doing per week turnover wise as a one man band full time.  Without a decent van setup i currently do £150 on a winters day - Trad + WFP Trolley.  I'm thinking that £750 per week is manageable 4/5 days a week especially more so Spring/Summer, what do you think?