It's pretty rare today to find a decent house for under $100/sq ft in
many areas of the country.


"Decent" is a moving target, generally meaning something like:
"just better than I can comfortably afford". I got a 5000 sqft
ex-masonic temple for $125k. Of course, there was heat only
on one floor, asbestos everything, one toilet, and no stove,
but for me "decent" meant "not likely to fall down, habitable,
in a place where the building inspector isn't a nutcase."

Other people have different standards.