British company Pod Space makes and sells prefabricated garden buildings that were designed to be used as guest rooms, studios, and home offices. Compact eco-friendly pods will fit unobtrusively into most backyards and larger models will accommodate up to four adults. They come with integrated workstations, lighting, and bookshelves.
MOSS is a Solar and Wind Powered Prefab Office That's Perfect for the Backyard... maybe perfect for a studio as well??! http://inhabitat.com/moss-is-a-solar-and-wind-powered-prefab-office-for-backyard-employees/