At around 100,000 miles they should be looked at (not necessarily replaced, but its on the service sheets for an inspection), and generally higher mileage cars would usually benefit from a PCV overhaul, so in my opinion cars with 130,000 miles and over should consider this if its never been done as a rule.
We can supply PCV 'kits' that we put together, consisting of the oil trap, all of the hoses and hose clamps, the breather tube and an inlet manifold gasket. Prices do vary widely depending on specific engine details, if any one is interested please send us a parts request following the link in my banner below.
(Currently we are still extremely busy so I have not been able to reply to everyone as quickly as I would usually like too, but I am doing my best so please bear with me!
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Simon