I fitted them to mine about 4 or 5 years ago. Starting to fade a bit now. They are called anti rattle clips and are a B7 S4 part not B6, I'm sure the part number is on this forum somewhere if you search previous posts, I may have posted it myself.
Cost was about £50 odd but that was a long time ago and I can remember reading somewhere recently the price is a lot more than that now.
Pretty easy to fit, just make sure when removing the existing one that you cover it with an old towel or something similar as when you pry the old one off it will try and launch itself in the general direction of your face.
