Kenik,
I'd concur with Jeff A; billet items do not necessarily translate to a high-dollar investment however,........in some cases, the price reflects the number of hours invested in engineering, prototypes, materials, and the volume.
When it comes to manufacturing, things are not always as simple as it might appear.
The Rothsport ones are prototypes and do not necessarily reflect the final product. Further, these will be designed to assure that the coils cannot fall off the plugs under racing conditions on the top as well as the bottom.