Try ebay, lots of genuine Audi stuff on there, a lot of it brand new. Search on 'genuine Audi'.
I got a pair of brand new genuine Audi front carpet mats, still bagged and fastened together for less than half dealer price and that included the postage! Absolutely no complaints at all. Usually are lots of brand new carpet mats on there. Plenty of wheels too where people are doing upgrades immdeiately on buying their new car.
As I posted last week, there are a couple of franchised Audi dealers selling stuff on there too now at less than rrp, though I don't know how competitive they are.