Just bury two of these in the yard upside down and and secure base with concrete. Cut and add a hatch and pour concrete and rebar 1/2 a foot thick on the top, dig 3, 1/4 feet deep under your lawn and have both containers connected by another hatch. One side is for you and your family, other is for poop and food.

Seal chamber completely with silicone calk and keep 2 gallons of hydrogen peroxide in a container. Use a uv flash light to decompose the hydrogen peroxide into oxygen over the two weeks youre in there. Buy a surplus re-breather to share between your family (20min ration for adult, 15min for child).

Bring Nintendo DS and bible.

$900 bunker