Youtube has almost everything. I just discovered that there’s a channel filled with easy and cheap, built-in-yourself projects including simple cabins. The Tiny Yellow House channel is here:
There is even one he calls “a writer’s retreat,” although it’s best only if you like a lot of light. Derek Diedricksen is the author of:
Lots of interesting projects and the tiny yellow house ones will link to similar projects by others. Some only cost a few hundred dollars and are designed to be easy to build.
A get-away-and-write cabin at the back of your lot for quiet in a noisy house. That’s the best option since you have easy access to all the luxuries of home.
A starter cabin for a place in the woods. Live in it while you build something larger.
Build one on wheels and use it for a camper van. May it small/light, and you can pull it behind even a small car.