> You also can't just construct your own shelter that you find adequate. It has to reach the very stringent and remarkably expensive building codes that exist virtually everywhere.

Not really. Most of California has no building codes. From what I understand, you could buy land in the desert (or honestly, just squat, no one cares) and even if you went the legal route, no one cares if you do whatever you want.

Of course, all the desirable land is taken and expensive because you'll have to convince someone else to give up its use to you.