OK, so a few of these homes may be too tiny to live in full time. Nationwide Homes markets them mostly as guest cottages and vacation homes, and the smallest, the Starling, is only 250 square feet. However, if you’re single or thrive on family togetherness, other models could make for some year-round “cozy” green living. Certainly the price is right, and they’re available anywhere in the country. One is the Osprey (pictured), the largest ECO-Cottage. At 513 square feet, it comes with one bedroom, one bath, tall windows for natural light and a porch. Green features include a tankless water heater, high-efficiency insulation, and a long-life metal roof. Optional eco-features: bamboo flooring and solar panels. The Osprey retails for $59,900 (not including delivery, taxes and installation). Final costs depend on your location, builder, etc.