I only have third party insurance, so had to pay full price for the screen. For the V5, with the rain sensor and all stuff, I had to pay £205 from Auto Windscreens. Autoglass quoted me £550!!!
The annoying thing is that fully comp insurance for me is only £230, but because I had third party cover on my old car I couldn't upgrade without losing half a years NCD.
One tip, check the wipers are secure after they've finished. I had one of mine come free of the splines at 80, in heavy rain.