I mention "designer" since there is a pre-fab market for non-designer homes, which do come pretty close to the mission of being a better value without being a "mobile home" - think Pratt, etc.
Ultimately, we went stick-built on-site and paid roughly 35-50% per sq ft of what a comparable pre-fab designer home would have cost, while allowing us to focus costs on the aspects of the house that mattered most to us, while going budget where it didn't matter as much, and still having full control over the process. FWIW, for less than the price of this unit alone, we had a full custom 1,200 sqft house 3BR/2Bth, metal garage, 800' driveway, well, septic, and 1-acre pond built.
I can see if you're willing to pay the premium on the design aesthetics, but designer modular houses have a long way to go to being a more affordable option for most buyers.