As for the power supply fan, you are probably better off getting a modern ATX power supply for $40. Here's how to make it work: http://antelopearcade.com/forum/yaf_postst4_Pinball-2000-AT-to-ATX-Power-Supply-Replacement.aspx
As for the CPU fan, it is an Evercool 50X10mm Fan (3pin, EC5010M12CA) which is still available (Amazon, Ebay, or Newegg) although any 50x10mm fan will work. It's best to stick with a ball bearing fan for reliability, which the Evercool is.