get the alternator from Pelican parts if you cannot find it cheaper in the UK.
http://www.pelicanparts.com/cgi-bin/...Each%2520%2520
I checked the part/no above with the realoem and its correct.
p/n: 12317831436
I brought a starter from them a few months ago and they are very professional and delivery was prompt and you get to track the thing from start to finish.
Hope this helps. Well cheaper than 800+.
P.S. remember to tell them yours is a UK RHD so they can double confirm the correct part is sent.