Hobbit Hole

I saw advertised a 7'x7' shed shaped like a hobbit hole on sale. It costs around $3K, give or take, and it would make a lovely play house for a child.
It brought me back to one of my dreams for a different lifestyle, which I have had recurring from time to time, to have a very small home on a bit of land where I could have a garden, grow my own food, and conserve energy (and expenses) by condensing the indoor space needed. 
I've often thought that a trailer or shed would do me, but the gardening doesn't really cut it for me. Not anymore, at any rate, as I have to take too much time off because of my back (and general pain) - not to mention my bi-polar, which often times has left me motionless for days at a time.
While I'm staying here, I have time to decide. Once she graduates from high school I want to move on, and so will she - She'll be 19 and on her own. I'm not going to prolong things this time. 
I was thinking of a small room somewhere - a studio maybe, where I can condense things down and have just what I need - and no more. No crafting supplies or equipment - no room for someone else to move in with me. Just enough room for sleeping, watching tv, reading, and eating. 
I'll be 60 years old by then, and I don't want to have to take care of anyone anymore - ever! I definately don't want to life here too long.
So, I'll talk to my mother about moving into a retirement community and I'll start looking for somewhere to go - preferably somewhere near the water so that I can take walks along the shore.
If I'm lucky, I'll find something slightly larger than a hobbit hole, but small enough that no one will try to move in so that I can take care of them.