Back in the 90's I designed and we built a passive solar straw bale house, complete with greywater system, composting toilet, and water heating using the wood stove (which was our only source of heat). Since then, I have written this book on how we did it on the cheap. Back then we made the complete shell and moved in (still working on the inside) for $20,000. For anyone who is creative, or resourceful, it could cost less, or around the same today (inflation lately is an issue though).
The book is two in one (passive solar home design, green building and straw bale) and focuses on design, finding used and free building materials, and having a good plan before you start. We lived in Nebraska, so the rules and codes were in us working with what we had there at the time. This book has suggestions and checklists and helps you think about how to save money and do things yourself by designing smart. Building our own house was not easy, and it took us time (a few years), but it was worth it in the end, despite that we moved away later. My friend who bought the house still lives in it (since 1999).
Here is the title and link for the book, for those who are interested:
Cheapskate's Passive Solar Home Design for DIY Straw Bale or Green Building:
Thrifty Ways to Barter and Find Cheap Used & Free Materials on a Frugal Budget
https://www.amazon.com/Cheapskates-Passive-Solar-Design-Building/dp/1717523536/ref=sr_1_6?crid=AHKVTBWFQRGU&keywords=sharon+buydens&qid=1655416712&s=books&sprefix=sharon+buyden%2Cstripbooks%2C248&sr=1-6
