I would not waste much time searching for Papst fans. If you happen to find some for sale at an electronics, or product liquidator thats great. The prices of the Papst fans from a distributor are very high. I'm talking $28+ per fan. I have found them for retail sale at several places and the price was always about the same. If you get lucky you can find them for around $4 from an outlet, but they usually are high CFM, high dB models , not intended for PC use.
Instead of searching around for hours on end for the perfect fan like I did, just buy Panaflo's from
Team Awe or maybe find them at an outlet. Either way Panaflo's are much cheaper, quieter, and better suited for PC use.