Best place to order univalve from?

As per title, where is the best place to order one from? I've found them on ebay for £38. Never bought one before so not sure if that's the going rate. 

Mate of mine showed me his a few months back and since then I have been meaning to get one, just not actually got round to it! 

https://www.wintecs.co.uk/water-fed-pole-window-cleaning/water-fed-poles-and-brushes/unger-nlite-one/ex-ceed-innovations-uni-valve-auto-flow-control/

2 for £27 each

That's lovely, thank you ?