You can also use a 2 or 3 speed hair dryer. A 3 Speed dryer is better but if you can't find one a 2 speed dryer with tied into a rheostat works ver well. I picked up a replacement blower for 5 dollars at the local Goodwill and on low speed with the rheostat turned all the way down I have a nice flow that keeps me at a decent working temp. When I turn the rheostat up to full I can reach welding temps very fast.
I also like the vehicle ac/heater blower idea as well. If you can scavenge the speed control from the dash as well you can easily adjust the speed of the fan with only a few minutes of wiring to tie them together. And if you are like me, a car battery and a solar charger from Orielly Auto works as a great 12 vdc supply system.
