I think you would probably make a lot of sacrifices for 252 square feet. That's a square 15 feet on a side, smaller than a standard 2 car garage. My dad lived in a 40 foot motorhome (8 ft x 40 ft) and that's 320 square feet and it felt small when I stayed in it; plus, most everything was motorhome-sized (stove, toilet/bath, etc) and a lot of built-ins & storage efficiencies.
This guy says he has a wife and 3 kids -- I think it might take some religious type orientation to live in a cold climate with 5 people in 250 sq ft of space.
The most bare necessities like a toilet, sink, tub, bed, stove, fridge, table, chairs add up pretty quickly. I didn't dig around enough in his web site to see if there were inside pictures, but I'd be curious to see how its arranged.
My biggest beef is just that the poster was disingenuous -- "I built a stone house for $7k". What he built is smaller than most garages and approaches a large shed in actual size. I'm also skeptical $7k can actually cover building, furnishing and decorating even that small space completely. Maybe if he moved in existing appliances. Maybe if he built all his own case goods. Maybe if the finish materials are like prison-basic (just coating the slab with a gloss topcoat instead of tile or carpet), white paint on the walls, etc