Following my first post on build-it-yourself lower cost housing thoughts (building using shipping containers), here is another option: 3D printed houses. 3D-printed home builds are created using large 3D concrete printers. These are starting to appear around the World; the print machine is generally run by a construction company. A home printed this way can mean much lower cost for creating the structure (especially useful if there is already a printing machine being used in your area or the area that you wish to move to). I read that it can be possible to build a basic house structure (not including the finishing & inside decor) in as little as 24 hours. Examples of finishing decor still to be added to the basic structure at further cost: think windows, doors, pipes, electronics & other furnishings.
A search for photos on the internet using search terms like “best 3D Printed homes” will already bring up classic/standard looking homes as well as creative/futuristic designs. It appears that many (but not all) of the current home designs are for one-story homes.
One of the first things to ask is whether local zoning permits them. Also to be checked is if the intended home would be insurable with house insurance. If you find a builder or architect already working with this type of home construction, they are likely to have some handle on the zoning & insurance questions (or how to check on and/or approach these questions for your intended location).
Some idea of basic structure cost: depends on how complex & large a home you want, of course. As an example of starting costs for probably a very basic structure, I have read that one might be able to have a simple 1BR structure built for USD15,000, & a basic 4BR structure for about USD50,000 (plus the cost of land which varies depending where the home is built, & plus the finishing costs). Costs for the structure go up from there, depending on how complex a design & how large. If building permits etc. allow, perhaps one can even start with a smaller home & then add on later to make it larger.
If contemplating such a home build, I might suggest: ask Lots of questions first. Talk it over with one or more professional builder(s).