Boxabl vs Addition To Detached Garage for ADU

[Greg Kitzmiller]

I have a property with a detached garage that's partially converted that I want to convert to a living space. I've talked with architects and contractors and have gotten either a lot of friction or >100k estimates to add a bathroom/kitchenette to a detached garage. 

Boxabl for $50k seems like a simple way to cut through the labyrinth that an addition seems right now. 

I live in Portland. Is the above a good assessment or am I just not finding the right people?

if I'm on the right track are there any good alternatives to boxabl?