[bombcar]

You can buy kit houses that basically do what you're describing, up to and including entire log cabins that go together like Lincoln logs of yore (which end up being MORE expensive because they literally build the house at the "factory" and then disassemble it, put it on a truck and reassemble it onsite).

The big problem with kit homes ends up being what happens when (not if) you @#$@ something up.

And the big builders are already bypassing Home Depot, they buy from suppliers that you've never even heard of (the smaller ones buy from suppliers you've heard of, but when you went in everything was 5x the price of Home Depot, because they don't want you as a customer - they want the builders who buy on account and get 80-90% discounts on "list price").