I'd be up for trying this if I could get it for around 250-300k for the 4br and then that allows me to pick up the land for 150k and come out about 150k cheaper than a standard house, but you're expecting me to pony up 500k + whatever it costs for the land plot, when I can just buy a house for 550k in the same neighborhood prebuilt.
My point is, your value prop isn't real. It's a great home, and a great idea, but it's actually more expensive square foot for square foot.
My wife and I are going to be house hunting in the next two years, and we would have considered this option but it's actually more expensive.
You can give the standard Tesla "but you'll have lower (gas/electric) bills" argument but I like air conditioning, so I doubt that's true for me, and even if it was, it doesn't really sell me either. "Because you'll save so much in the long run(and we can't really prove you will), you need to pay an extra 150k up front!" doesn't ring well.
EDIT: To clarify, I basically feel like in order for this business to work at all, it has to be a much cheaper option than a normal home, because there is an accompanying huge risk in investing in one of these. It's resale value may be next to zero, and all it's fancy gadgets will be out of date by the end of next year.