Do you have any surplus electronics shops in your area? This is the type of place I'm talking about
:
http://www.skycraftsurplus.com/
I go there when I'm in Orlando, I can usually spend a whole afternoon there browsing all the cool stuff. Even their 5v 25mm fans are still $2.50 each. I think you might have a hard time finding them for less than a few bucks a pop.