$30 and ALOT OF TIME! Half the materials are scrapes. But the build is pretty neat. It only has one axis to worry about for a vertical mill. and seems pretty productive. I wonder if I can find a smaller bike wheel if I could make a smaller version of this.
http://www.instructables.com/id/Vertial-Axis-Wind-Turbine-from-30-Of-Scrap-Materia/