I haven't used this particular one but I have used something similar. This is a link to various vehicle breakers around the country, you fill in details of the part you need and the breakers that are linked to the site can view your request and if they have a matching part they get in touch with you. I needed the mechanism for a drivers side wing mirror after it was hit by a big motorhome and it fell to bits - the casing was (surprisingly) totally undamaged but I was told by the dealer that they didn't sell the bits for the mechanism seperately and I needed the whole lot at about £198 plus painting and fitting ! I used breakerlink.com and the same afternoon a breaker contacted me to say he had a electric/heated mirror for £70 including delivery. I ordered this and the next day it arrived, and 10 minutes later my mirror was sorted. So my experience was a good one.
PS - if anyone needs a drivers side wing mirror casing in blue let me know - I didn't need the casing just the mechanism so if you have a damaged casing I have one going spare.