Does anyone know best place / price to get a new VVT Pulley for my freshly rebuilt 20v ST?
 
Didnt realise they were sooo expensive.. Does anyone know, other than the diesel noise they make when they are bad if there are any other side effects running the engine in this state?  Aparently it is a know issue on both the ST & BT engines.
 
Performance doesn't seem as it has been effected in anyway.. apart from the annoying tapping noise. 

There is no loss in performance or functionality from my experience with a good and bad VVT pulley.
Swapping in another second hand one is likely to leave you with the same results shortly after and spending the cash on a brand new replacement is better spent on some huge cams and adjustable cam gears.
 
TL;DR - Just leave with it :)