For the first time home buyer in San Diego (as I am), it can be hard to find a modern, energy efficient, single family home for less than \$500k. Especially when you also want some acreage (as I do). So I'm considering having a house built, in a year or two. I want it to be energy efficient, possibly net zero, possibly passive, and possibly capable of being off the grid. I also want it to be somewhat modern, to look good, and be high quality. All of that is hard to find at a decent price. Which is why I started looking at prefab and modular homes.
My search started with Prefabulous + Almost Off the Grid, which includes lots of beautiful examples and plenty of references. Combined with my own research, I've put together a list of the prefab/modular home builders in the United States. I've included the location and year founded, when it was easy to find.
All of these are "affordable" to some extent. All of them have floor plans of at least 1,200+ square feet and I'm not including cabin kits or anything else that's too small to be livable for a family of three.
This is a pretty exhaustive list, but if there are any I'm missing, please let me know. I plan to investigate these further, starting with their price per square foot and which options that have available.