A Mexican entrepreneur founded a company called EcoDom, which develops products out of recycled plastics and card boards, and even built houses for low income families. These houses are amazingly cheap, as a 42 square meter house would cost 265$ and the buyers are allowed to pay with work instead. While they are cheap, their load resistance is up to twice the traditional materials.
You can find out more about this new environmental enterprise company in their website.
Houses built out of recycled plastics