Nice incubator. You can make one of those fans really easily for under $10 shipped.

http://www.allelectronics.com/cgi-bi...LING_FAN_.html

http://www.allelectronics.com/cgi-bi...NSFORMER_.html

Just cut off the connectors on the fan and transformer, then connect them with a little electrical tape. You can buy two fans and connect them to the same transformer to have one blowing up and one blowing down to circulate the air, too. A small switch can be added anywhere in line so you don't have to run it all the time.