Having had several sets of intake manifolds made over the years, I can give some insight on what you are up against. The first photo shows the original manifolds I bought on a group buy about 10-15 years ago on the pre Yahoo Europa group mail list. The top red anodized manifolds were the original pair with the two bottom pairs, duplicates I had made up by my original machinist, now retired. He did a good job duplicating the original set. He was old school, all manual operations on the milling machine, no CNC setup. The amount of labor he put into the job must have been huge. With no drawings to refer to, all of his measurements had to been done with the actual manifolds with multiple operations and setup time for each operation.. After all that work, he only charged me $450/pair. Obviously I got a huge discount on his labor costs. The second photo,shows the manifold on a TC engine. The two manifolds were sold several years ago.
The next pair of manifolds, I decided to make myself. I have a friend who has a Harbor Freight mini milling machine who was willing to help with the project. We purchased an aluminum plate approximately 2"x 4"x 12", enough for two manifolds from ebay. With his experience in CAD, he made up a set of drawings for his milling machine with a CNC setup. He modified the original to eliminate any extra aluminum and picture three is the result. His comment was that his mill was at its limits machining out the manifold. The only costs for this project was the aluminum plate, water jet costs for cutting out the blank, tooling costs for the milling machine and his time. We managed to sell this version for $400. I suspect we lost money on this endeavor.
So the bottom line is that it won't be cheap having the manifolds made up by a machinist. You don't have an example for the machine shop to examine to take measurements for a design. You should at least have a drawing of a design for a machine shop to refer to. Your best bet is to follow up with Barry Spencer and check out his design. From his website, his manifold looks pretty basic with minimal amount of frills and his price isn't too bad compared to what I sold my manifolds for. Just make sure they're mad from aluminum and not plastic, though that won't be a deal killer since there almost no other alternatives available. In the meantime use the stock secondary manifold until you come across someone selling an alternate manifold design.
