Make a vertical wind turbine for under $100. by Jeff Berezin via youtube
Notable is that this cost less than $100 in materials so far and that the largest part of this turbine is recycled materials (the PVC drums previously held Balsamic Vinegar from Italy).
Also, this turns well in a very light wind.
Axle: 3 inch PVC piping from Home Depot
Bearings: 5 inch lazy suzan from Lowes.
Part 2 will cover power generation and connection to the battery bank.