Yes, mate.
A shurflo back pack from around £160 to £215
See here:
http://cgi.ebay.co.uk/BRAND-NEW-SHURflo-Rechargeable-Backpack-Sprayer-SRS-600_W0QQitemZ7744927159QQcategoryZ75582QQssPageNameZWD2VQQrdZ1QQcmdZViewItemThen have a look at this site for a full explanation of how it all works and recommendations for for RO/DIs, poles and stuff:
http://d.co.ukAs a rough guide for doing first floor and above, you'll need the following:
Back pack: = £215 (£160 from E-Bay)
RO/DI (60 to 70 Gal per day) = £70 (ish)
200 litre Water butt = £40 (from your local garden centre)
Water Barrels X 5 = £25
Pole & Brush = £120 (make sure you get a good quality one; I'd suggest an 18 foot three section brush)
Hand held TDS = £13
Argos Shopping trolley = £10
Hoselock conections = £12
The above adds upto £505, but I may have missed VAT or P & P, so budget for £600.
My set up is very similar to the above apart from I have two two-hundred litre water butts, more barrels, and a 200 Gallon Per Day RO (but I only 'switch' it on for a couple of days a week).
After your initial cleans where you'll use lots of water, doing 'tops only' (leaded and Georgian excepted), you'll not use more than 100 to 125 litres per day (4 or 5 barrels).
It's all tax-deductable, so you've nowt to lose.