The cover with light separates from the mechanicals of the mirror.
There are electrical contacts between the two parts as well as a wiring harness that's part of the mechanicals.
If contact doesn't happen, one needs new mechanicals.
Attached is scan of the fiche from EPC. Right side of fische shows mirrors with integral turn signals. The light unit is NOT a separate part.
Mechanicals are 220 810 08 76 and list price for this part is $250 and it's $195 here:
http://www.trademotion.com/partlocator/index.cfm?siteid=213951
List price for cover/light is $190 and Duval is $148.20 but you have to order 220 810 10 64 with a color-code.
You've been given the correct story and good prices.