The design and practicality of new collider options being considered to supercede the LHC at the high energy frontier will depend heavily on the superconducting main dipole magnets. As a major cost driver, these magnets must be highly optimized between cost and performance in the context of the entire accelerator. Realistic cost models need to be developed as a guide to the magnet development effort towards the most cost effective technology. A basic cost model will be proposed that also takes into account the impact of the chosen magnet technology on the overall cost of the accelerator.