OK, this is just cool. I've always wanted a greenhouse to grow veggies in, and this one is specifically developed to work in places where even a greenhouse might get too cold.
http://www.treehugger.com/galleries/2009/07/build-a-geodesic-dome-solar-greenhouse-grow-your-own-food.php
I figure he's spending about $500 per tomato.
You could, I think, convert a hexayurt into a much cheaper greenhouse, G.
http://hexayurt.com/