Housing For The Birds

From Business Week Online:

Designer tree houses are a personal way to add fun and value to your home, and they're not just for kids anymore. This next-generation tree house is a prefabricated modular structure that is fully livable and can be adapted for a family of up to eight.(lower photo)Free Spirit Sphere by Tom Chudleigh, Errington, British Columbia
About $44,700 to buy and install; $134 for one-night rental