A quick recap on what I bought/did: 4 LHD LED lights @ €365 + 4 ready made cable connectors @ €39, all from eBay Germany (nearly all German sellers speak English). I posted example links above, but otherwise do a search on ebay.de using
golf gti led heckleuchten or
rückleuchten, don't forget the dieresis (the two dots over the 'u'). All parts are genuine VW.
The physical install is so easy that even Kev could do it; all the lights work instantly. However, you get error messages on the MFD when you start, plus a permanently lit yellow warning light on the dash. If, like me, you can't live with this irritation, you need to alter the coding using VAGCOM, as SteveP has said. My dealer managed to do it, but it took them a while to figure it out, even with the coding I supplied (there are millions of 0s and 1s in there). They didn't charge me, but I gave each of the two technicians €15 by way of a thank-you.
Total cost, therefore: €434 / approx. £380
VWKev, if this is still not information for you, take a look at SteveP's massively detailed write-up here:
http://mk6.mk5golfgti.co.uk/forum/index.php?topic=81.0P.S. the guy who sold me the lights in Germany also threw in a rather nice GTI beach towel
