Near VAWT. I wonder if they just sell the turbine?
A 3-d printed VAWT that uses old plastic shades for some parts.
A box fan wind turbine. NOTE: box fan motors are not normally DC motors. You will probably have to swap out the old motor for a DC motor.
A PC fan wind turbine. These are often DC motors but not always. Check the motor carefully. You need a DC motor for generating electricity easily.
And another one that looks easy to make out of PVC tubing glued to plastic sheets.
Here's a style where you can use winder PVC pipes instead of having to build them.
More news about clean power: CleanTechnica.