Cost to replace timing chain guides/tensioners on M62 (4.6is in particular?)

[Adas]

Hi everyone,
I know that this topic has probably been discussed TO DEATH on this forum already... But I have yet to actually find a post or a thread where people talk $s.

I'm in the market for a nice 4.6is (so I'll double-up on this post as a plug for that WTB as well!) and there are a few around that have had the timing chain guides and tensioners replaced, but a few others that don't mention if it's been done (so take it as read that it probably hasn't).

I would just like to know - so I can factor it into my budget as an immediate maintenance issue because I won't want to drive around in a 4.6is without the guides and tensioners having been done - a ballpark cost on this work? I'm thinking by an independent specialist rather than a BMW dealership (although would be interested on peoples' experiences of both).

Thanks in advance - and like I said, if anyone has a really nice 4.6is that has been LOVED and maintained to death and they'd like to part with it, please let me know!

Adas