Contributing to thread:
Underground * Empty plots of land are routinely available for very cheap. I once bought a third of an acre in Lake Arrowhead, California with water, electrical and road access and less than 2 miles from a major freeway for only a few thousand dollars.
* Digging by hand is slow and miserable. Digging anything big enough to move around in with a pick and shovel will take weeks. Expect to spend your first day digging something up to your knees, then being too tired and missing too much flesh on your hands to be able to continue for a few days.
* To avoid all that, consider renting a
CAT. It will only be one or two hundred dollars a day and no certification is required.
* Construction, structural concerns, and much else can be vastly simplified via use of
steel shipping containers. Last I checked these are about $2000 each new, so it does increase costs considerably, but encase one of those things in concrete with proper drainage and footing, and it will be sturdier than the house you're in.
CastlesTo the people expressing interest in building castles, I suggest you look into
rammed earth. It is both easier to work with and much cheaper than stone, though not always appropriate in moist climates.
Buy one already builtIf the 6 to 7 figure price tag is acceptable, for sheer awesomeness, it's tough to beat a
Nuclear Silo.