I got started off with a starter kit from Window Cleaning Warehouse in Wolverhampton, think it cost me about £500 to £600 for everything (RO kit / tank / water fed pole / hose and reel / tds meter / all fixtures and fittings.
Then brought a water butt from B&Q and slowly added to my equipment over the last few years, replacing their hose with john guest fittings etc.
Although heavy, the pole managed to do every job i needed to (although i have since replaced with an SLX), the RO unit and hose and reel are still going strong.
I had similar budget woes, but if you work hard canvassing you can earn a living and pay that off in six months.