Last I checked 5 or so years ago a lot big enough to drop a yurt on in San Francisco was only like 100k. Legally unbuildable, but perfectly usable and sanitary with an incinerator toilet, solar, and hauled water. Maybe 200k all in, in roughly the most expensive place in the US.
If it's legally unbuildable, does that mean you're spending 100k just to get yourself imprisoned for having an illegal structure?