I have genuine ones and I'm really happy with them. I've used Thules before on several cars but find the Audi bars just a tad better, quiet, more secure and better overall fit. The rubber feet in particular I think are much better thought out and fit great. The only downside of them is that the bar does not protrude beyond the foot so could limit how many bike racks etc you could possibly fit compared to Thules.
I picked mine up on another forum for £25. I've seen them on Ebay occasionally also A4 B6 ones are the same for the B7 so might broaden your search.