A lot of this about, a part for an Audi will cost more than the identical part used in a SEAT. It's not just VAG parts either, the Jag S type and X type use a lot of bits from the Ford parts bin, prices are much cheaper if you can buy the Ford part instead.
Best I've come across is the aerial for a B5 / B5.5 Passat, they deteriorate after a few years and look really scruffy. Buying on eBay, a Vauxhall Vectra one is exactly the same item but costs less than half the money from the same seller.