If you want to keep it simple, you can order whole kits from Tree House Supplies or Treehouses.com, which include everything you need for a particular treehouse. That is, everything except the lumber.

A backyard hideout is a childhood wonder. If you always dreamed of your own treehouse as a child, consider fulfilling that wish by building one for your own kids.

But to get back down to earth: You can find a simple, ready-to-assemble kid’s treehouse for as little as $400, according to home improvement network and information company Angi.