The only place to get one is from TPS (volkswagen parts service).
I paid £354 inc vat for mine.
Do not under any circumstances put a used one in your car unless the original tappets come with it. The cam will wear out in 3/4k as I tried to just replace my tappets and not the cam and the new lifters destroyed the cam lobes in 3k.
Same applies for the tappets too, if you need a new cam do the whole lot.
I paid about £750 for everything fitted.
If you cant stretch to that then AW Engineering sell cam kits of £300 plus vat which includes the cam and tappets but be aware if you did not know that you will need to replace the cam housing bolts and the roller rocker bolts as they are stretch items and should not be re used.
Plus an oil change too!
Glynn