The track rod complete with track rod end is about 80 + vat from Audi.
The track rod end only is 22 + from audi IIRC.
You can get ebay track rods and rod ends for about £25.
I am not sure of the quality of the ebay or GSF/ Eurocarparts ones, but I got an audi one.
On my mk4, I fitted Vw genuine ones. Why, well, they are a pretty important part and you only tend to need them every 80-100k miles!