I built a tiny house on wheels. My house totaled about $55K, due to my preference for premium materials and contracting out work that I did not feel comfortable doing myself (e.g. wiring a 50amp power box).

My house was built to be on grid and could be parked in any trailer park. I could connect to city power, water, natural gas, and sewage.

Off-grid homes are more expensive due to the need to install solar panels, drill wells, bury a giant propane tank, and purchase land.

$50K is honestly one of the cheapest builds I've seen for an off-grid cabin. Their house looks amazing.