I get them from the dealer. I think they come in two different colours, blue for one side black for the other, can't remember which is which.
http://www.vagcat.com/epc/cat/au/A8Q...57/56/3259265/
VagCat says:
36 4D0854721 clip left /
(36) 4D0854722
So I assume its 4D0854722 for right side, best to check with the Audi dealer though.