Hopefully this will clear up what is OEM and OE. There is also a list of manufacturers that make OEM parts for Porsche, water pumps being one of them.
"OEM Porsche Parts�stands for "Original Equipment Manufacturer". Porsche OEM Parts refers to the company that originally manufactured the product for Porsche. When referring to OEM Porsche parts, OEM designates a replacement part that is made by the manufacturer of the original part from factory. Believe it or not, Porsche does not manufacture and produce many of the parts they use to build their automobiles. Like most carmakers they use outside independent companies to help them design the parts used in your Porsche. Porsche then puts the parts in their own boxes with their logos.

How do these parts become available to companies, like ****************************************, to be sold to the end user? After a certain time frame the actual manufacturers of these Porsche OEM parts are allowed to sell them to other wholesale distributors for resale. This time however they come packaged in a box with the name of the actual manufacturer of the part, not Porsche. Its not an inferior part its just put into a different package. In most cases the part will be identical with the exception of the packaging."
Porsche OEM Parts - Original Equipment Manufacturer, 911, 944, 996, Boxster

Do you really think he cares about $100 in the cost of a water pump?
The Pierburg pump is the same as the Porsche branded pump

As far as his profits, well it does not take a Rocket Scientist to guestimate what the profit might be. @ $20k+ for a replacement engine from Raby when other replacement engines are in the $8-$12k range it's not hard to figure that he is making $10k ish. Sure, Raby does more in his engines and does probably replace more components than some others, but he has even stated that he raised his price somewhat because of what the market will bear

I am not saying he is not entitled to make a profit at all, in fact he is 100% entitled to make whatever he can.
Is Raby one of the top M96 experts in the world, YES
Does he build a great engine, YES
Is he making major bank, YES

If you research his old posts on this topic, he will not use or recommend a Pierburg pump. Only a Porsche pump in a Porsche box.

Which could be any number of pumps supplied by OEM and authorized by Porsche to be boxed and numbered as a Porsche part. Porsche does not make water pumps they rely on a third party supplier and probably the one that gives the best price point. Jake Raby can call what he uses whatever he wants it is his business.

so what???
drink whatever Kool-Aid you like