This is super helpful, I have tried to reflect this better in an updated title. The shelters I am fairly certain can but built for this material cost (not including labor as in a pinch I think these could be made by a wide range of people, perhaps even by the inhabitants themselves). But it is right that cost effectiveness is much harder than simply summing up material costs—one would have to cost the total solution and also have some grasp of the reduction in x-risk, which is far beyond the scope of what I have done. I simply found a physical structure that seems quite robust.
This is super helpful, I have tried to reflect this better in an updated title. The shelters I am fairly certain can but built for this material cost (not including labor as in a pinch I think these could be made by a wide range of people, perhaps even by the inhabitants themselves). But it is right that cost effectiveness is much harder than simply summing up material costs—one would have to cost the total solution and also have some grasp of the reduction in x-risk, which is far beyond the scope of what I have done. I simply found a physical structure that seems quite robust.