Came across a more "reasonable" small bug-out cabin at Simple Solar Homesteading. Owner built for $2000. A little rougher than the Tiny Homes mentioned previously, but a lot more practical.
Small Cabin covers one guy's experience building an inexpensive cabin in the woods. He totals up $1256 in materials for building his cabin, though has no power system, appliances, or plumbing from what I could see. He uses a wood stove for heating.
I've personally had zip in the building construction department, so it will be a while before I tackle building my own cabin, but I'd love to give it a shot. But, if you're willing to "do-it-yerself", there are lots of examples, kits, and plans out there on the internet to help you on your way.
Obviously, you don't need to drop $50k on a 100 square foot home--that money could easily equip an entire family, purchase a BOL and build a modest, livable cabin (or three).
