Kent Griswold has setup a website dedicated to the Sonoma Shanty. You can buy a kit or finished house from Stephen Marshall at Little House on the Trailer or the plans from Kent at Sonoma Shanty. Kent has posted several larger views of the plans themselves at Sonoma Shanty for those of you that want to get a closer look at the plans. Here is a recent testimony by Nick from Indiana who bought the plans:
I have to say I am rather impressed with the plans, the ability to mix ease of construction and functionality in this design is really pretty amazing. Example, using the 12/12 roof, provides simple construction and yields sufficient loft space. You’ve also eliminated the need for a birds mouth. These are all things a person new to construction would likely mess up. For those of us who have previously built such things, the elimination and simplification of these adds significant time savings, less room for error and waste, and ease of assembly. I am very satisfied with the plans.