That would be awesome, but that assumes he still has access to the tools to machine the parts with.

I doubt it.

I would assume that if he did, he could work his day job and just machine parts as they where ordered with minimal up front cost.

I imagine he was having a machine shop do it based on his plans and had to do stuff in large batches to keep costs down, which is a large up front cost and sitting on inventory hoping someone buys something.

Something like that I'm sure. If one doesn't have to pay someone else for the machining, the cost goes way down. But, one has to have access/own and know how to use a CNC machine.

One would also be surprised at material costs. High quality Aluminum tooling plate or strip stock ain't cheap. How thick were his? One inch?

I could totally make this thing but even I don't think I would do for $150 a piece, not anodized.

I have a brand new S5-S6 manifold adapter I bought in 2013, it's so nice I'm just going to hold onto it. If I would've known he was going to close up I would have bought a shitload of stuff to price gouge everytime this discussion comes up!