The only place that I can think of is ebay. Even though it has been getting a negative image, I still feel that good deals and odd items can be found.
You may want to contact MacDoc from this board as he may be able to help you (just a guess).
12" Apple PowerBook G4 - 1.5GHz, 1.25GB RAM, 320GB HD
Apple Mac Pro (2,1) - 3.0GHz, 5GB RAM, 500GB HD