Starting at just $25,000 (without, admittedly, a kitchen or bathroom) these nifty little eco-homes come equipped with green roofs and utilize sustainably farmed lumber. The best part about these is their versatility and adaptability – they are used for everything from doctor’s waiting rooms to garden work or play spaces alongside an existing home. On the architect’s website you can browse the many configurations, color schemes and programmatic uses that past customers have used. (Architect)