These reels or similar was on eBay for £240.
Unless you have health problems I can't see any advantage to this, it takes all of 5 mins to wind in by hand, and those that think £800 is a good deal, I don't get it.
If you have £800 spare to buy a reel then you must have already upgraded all your poles to gardiners very best first as more effort would go into cleaning windows than winding a reel in.