What do you consider to be "economical" Rob?

Tiny houses https://www.google.com/search?client...&q=Tiny+houses seem to be growing in popularity.

Have you considered a pull behind camper? A small motor home? A slide in truck camper?

A prefab or build on site utility shed?

And then we have straw bale houses https://www.google.com/search?client...71.XDtj0XPqy4Y.

Lots of options depending on one's definition of "economical".

O.W.