Every city has an expert contractor that can be had for little money to aid in the construction versus doing all this moving about.
Why not toss a few bucks at an expert to help build locally? But honestly, these things are not harder to build than a shed. It seems bizarre to want to build these things off site. They really are not meant to be moved about.
An ERE city, yeah, do that. I might even consider a second winter home since I live in Canada and it gets cold. Having a place to winter would be a nice respite and for 12k might be worth it. Then again, I might just pitch a tent if I was welcome versus putting up all that dough.
I thought a lot about doing the small house thing, but for harsh critical thinking the idea breaks down. Just the fact that you need a huge truck to pull them adds significant costs. If you're building on site, it would work. Getting together to build these things isn't useful.
Over the phone, via web interface, sending photos, etc. you can get all the expertise you need.
With all building, half goes to material, half goes to LABOUR (your savings because you are DIYing). Now add on top of this, extra cost of shipping and you might break even.
Costs of materials is small and not even big builders get significant savings over the regular guy. You might save 15% on your materials if you could buy it ALL from the same location. Unless you're going to build 100 of these, it's not going to amount to much.
If there was an interest, there would be a cheaper way to do it.