The price on the Check Valve that screws into the Vacuum Pump Body has risen to about $50.
From the pics I have seen of rebuilt and new vacuum pumps they come with a new Check Valve.

I did find the Piston end kits on eBay for about $170 each and the complete arm assemblies for about $350. So if you add those 2 together you have $520 (there is also going to be added shipping charges.) and you won't have a new check valve unless you purchase that separately for another $50. And when you are done rebuilding it yourself no warranty!

To me that makes the do-it-yourself rebuild not cost effective and you end up without a warranty.

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84 300D, 82 Volvo 244Gl Diesel