I would stay away from 120v AC fans. Inherently AC fans create heat. There are people that heat very small incubators JUST with an AC fan, but it is tricky. With a DC fan you just need a 12V power supply. I currently use a $65 120v AC to 12v DC power supply that handles 13 amps. A cell phone charger with 6v will run your fan at half speed of 12v ratings.
A simple 12v DC fan is sufficient. I use these 120mm fans.
http://www.newegg.com/Product/Produc...82E16835553012
At the bottom of this web page link on my website is a small wine chiller build.
http://cdconstrictors.com/?page_id=116
Latest custom incubator build.
http://ball-pythons.net/forums/showt...rogress-thread