A customer of mine just informed me that FEMA released funds for tornado shelters for the DFW area. Have not conformed as its not my cup of tea. Supposedly 50% grant up to $1500; ($3k shelter). Wonder if a human sized jewelers safe qualifies Great business to be in these days BTW.
You could retro fit shipping containers & bury them underground. A friend of mine bought a 40 ft. container for less than a grand.
That would be my thought. The process of setting it up would cost a bit more, but would be better, IMHO.