My folks did their own contracting when they built their retirement home in 1980. They subbed out the foundation and roofing. My father did the electrical and plumbing and my mother did the finish carpentry and stone masonry. I built the factory that made the prefab panels and drew up the floorplan.
They had owned the lot for 16-18 years before they built. They invested ~$70-90K, on completion it was valued at $120K and ten years ago was listed by the 2nd owner at $270K.
It's amazing what a motivated self-builder can do. In the 1970s I knew a lawyer that built a house with a stone wall first floor and upper floors made from timbers from a sawmill he'd torn down. Then he discovered his Rhododendrons didn't like the arsenic in the ground water so he moved into the Coast Range and did the whole thing a second time. It tires me just typing about it.
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Anyways that guy you showed built to the dominant paradigm. Big and full of corners that collect dust.
The folks place had a slab on grade, the shell of the structure went up in a single days barn-raising, then it was closed to the weather and all the interior work was done. It didn't stand open to the weather which promotes black mold in this climate. I've heard of people that built a house, tore it down and rebuilt and got black mold in the second attempt.
TLDR; Oregon Dome promoted conventional construction for the price of a mobile home. They just didn't have a clue about HVAC.
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If you can find a place that burned down, then you get the driveway and utilities without the demolition costs.