I had to have the camchain and tensioner replaced on my last 16v. The garage said that it made sense to replace the tappets while the engine was in bits anyway as it had over 100k on it. The cambelt was also done at the same time. The bill was a wallet worrying ?589, there were a couple of other small items on there such as replace leaky hose mount etc but I would say ?500 of it was the chain, belt tappets etc. The tappets were ?128 so you could save that by not doing them but it does make sense to do them while it's all apart anyway.
As for where to have it done, it depends where you are based, I used a vw specialist called cowley road garage in cambridge.