scubatoys:Depends on the reg.... If under warranty with some brands - the customer gets free parts... but in order for us to give them the free parts, we have to send the old ones to the manufacturer with the serial number of the reg. If the customer wants the old parts - they can have them.... but then the parts would not be free.
If you think the guy is not actually rebuilding the reg... I wouldn't bother ask for the old parts... I'd just go somewhere where you did trust the guys.
I'm curious which manufacturer you're referring to that requires the parts be returned. Regardless of manufacturer, the LDS where I work returns all annual service parts. This includes Scubapro, Aqualung & Apeks - the main ones that provide "free parts." The only parts that are returned are those with unusual failures (i.e. bodies, crowns, etc.) - certainly not items in the service kit. And, yes we do get reimbursed for the warranty parts. The only thing we have to do is fill out the appropriate paperwork.