As best you can, try to find salvaged or scrap materials. You can especially save a lot by finding second-hand finished components like cabinets, flooring materials or appliances. Find your local Habitat for Humanity Restore, a nonprofit home improvement store and donation center that sells new and gently used furniture, appliances and all kinds of building materials at an affordable price. Buy reused building materials at a fraction of the cost on Planet Reuse, an online marketplace for reclaimed materials.
Source: How To Build A Tiny Home On A Tiny Budget – Earth911.com