My standard for comparison is the Summit Structures tiny house shell.
https://www.summitstructures-or.com/
I had them price out a 10x24. That's a shorty single-wide. 240sq ft. for $20,000. If 480sq ft is wanted, I'd put two side-by-side with a 10ft garden in between. Fence with gate at one end and veranda/gallery at the rear.
Anyways, $20K for the shell and $10K for a clip-on utility module made from OEM Tesla parts plus solar hot water, and $2K for an Ikea kitchen and bath.