When we first started Armadillo, I bought a 100 lbf peroxide engine from Juan Lozano for us to test as a working baseline. He charged $1800 for it, and it was hand machined and welded. He would discount a couple hundred dollars if we ordered four engines at a time. We later had a batch of a dozen similar engines produced at a CNC shop. The machining (no welding was required) for each engine cost less than $150 each for all the components, and the shop was almost apologetic, saying the prices would get a lot better in lots of 25 or more. There was probably another $50 or so in catalyst screens for that size engine, giving us a total savings of 9x over Juan's motor, but that is comparing cost vs price, which isn't fair. Add your own markup to draw a conclusion.

CNC machining is one of the big advantages we have today over the early days, so designing systems to take advantage of it is wise.

John Carmack
www.armadilloaerospace.com