I found a used one on fleaBay for $55 shipped. I had been looking off and on but they are a lot of mislabeled taillights for the b6 and searches show the same wrong ones. So I looked it all over and found a printed on number covered up by a sticker, searched that number and lo and behold 4-5 popped up that I hadn't seen before and specifically stated Avant and had matching numbers as well as the light housing. My light housing now works but is severely corroded to the point one bulb won't come out without a fair amount of work. I used a hot solder iron to place some of the races back down where they had come loose also.I had the same issue with my taillights as well.
A silicone maker would be great to help seal it and it is reusable.