For kids, building a tree house can become an obsession. A private place to call their own, a high perch from which to watch the world, who can blame them?

Obviously, building a tree house is no small task--it must be done right for safety sake, and so you don't create an eyesore in your backyard. Hint: If you don't have much building experience, find a friend or family member who is handy, and willing to lend a weekend of his or her time. And then you must have a good stout tree with branches that spread in a V-shape, and is located away from power lines, the street, and other potential dangers. Before you start on a design, go to a building supply store to find out how much all of the materials will cost. Listed below are the materials needed and the estimated cost that we came up with (prices vary according to location and store).