The following advert has just appeared on http://www.windowcleaningroundforsale.co.uk
NEW ROUND FOR SALE
Region : South East England
Area : Buckinghamshire
Type : Domestic
Price : £100,000
Monthly average : £7,500
Established : 10 years
Comments : Excellent work with good prices. Massive room for expansion. Comes with 4 yr old Nissan Primastar, 650 ltr purified water system ,ladders and all equipment. Ready made lucrative business!
Please go to our website for more details
Think I need the euromillions tonight to buy this 
Well let's be really generous and price the van + system + other kit at £15k.
That's £85k of work. That's about 11
1/
2x monthly turnover for a well established round.
Presumably that would be two guys flat out if the work is well priced with perhaps a bit of "spare" work (or perhaps not if all the work is very well priced).
I suppose if someone already has money behind them and puts two good guys in the van it could be done but it does sound a bit on the high side.
I'm a person who believes that well established, decent priced rounds are worth a lot more than the current 2 - 4x monthly turnover they often fetch. Although a quality round may be worth nearly a year's turnover in extreme cases, I reckon they will have trouble getting it.
Hard to say really. If an non cleaning (or minimal cleaning) entrepeneur bought it he could run the business as it stands for £75k a year maybe so could break even after four years. That would be two fairly decent cleaners' wages, van + insurances, equipment renewals, plus someone seeking new work part-time.
Of course I've never done this so am only having a stab at the numbers but I bet I'm not out by a million miles. It would probably be advisable for the entrepeneur to have a small van handy for certain occasions which would entail more outlay.
It's the sort of thing I might have a pop at if I had a spare £100k (though I would try to negotiate some way on price). Perhaps a downward negotiation on price could cover the purchase of a part-time van that is used for private use the rest of the time.