I got replacement Bijur metering units for my mill from Lubetec. They do have a web shop, but it's just a generic skinned airline/pneumatics one used by lots of similar suppliers, and doesn't contain any of the lubrication stuff.

They do however have their own catalogue online, which contains all the centralised lubrication stuff.

I did consider the Arc Euro parts, however the threads were wrong and the genuine Bijur ones weren't that much more expensive. Just checked and they were £5.54+VAT each a few years ago, so not worth the hassle of retapping threads and changing fittings.

You'll need to get the flow rate of the existing metering units, as well as the thread/style/direction of flow if you need new ones.
I removed all the metering units from my mill, connected them up, and then left the lube system running overnight (it's an electric motorised one designed to lube every few hours). Any that were still dry in the morning, I replaced as they're pretty much impossible to clean properly once gummed up, and a few metering units is far cheaper than the potential damage from lack of lube.
One trick I did use, was to fill the system with ATF fluid and leave it running for a day. You can then check that all the slides have a nice coating of red oil, which tells you the system is working and getting oil to where it should.

For replacement pipe/fittings, I just used whoever could supply them. My mill originally had aluminium distribution pipe, which had corroded where it had been sitting in coolant, so I replaced it with the same sized copper pipe.