I got mine from GPC, genuine O/E part think they weighed in at £42ish with the vat.. a couple of points when fitting these, mine came about 5-6inches longer than needed, so will need trimming back, no tools are required to fit them, only a blade to trim them.
The seal easily pushes into the black metal backing, with the help of a little washing up liquid, as I had plenty of time on hand, I left mine out in the garden for a couple of days to go through a few natural heat cycles! lessoning the chance of them shrinking after they had been cut, and leaving horrible gaps!
Also take note (before you remove them!) of how the little plate is fitted that covers the join between the new rubber and the window aperture channel, you know, that little plate that's a few inches up from the door handle, it should sit perfectly flat and flush to the seals! amazing how many Golfs at GTI Inters this year had them fitted completely wrong...
Tom
