Ahhhhh....the fickleness of eBay......you can wait for yrs to see something and then four appear within a week. It's what keeps us all watching, I guess.....lol! 

You can stimulate a market on eBay to some degree too. In vintage stereo gear there were a few times I was collecting a particular something or other and bought most of what was out there. The almost immediate response was more of the same items than I had ever seen previously......plus a jump in the asking price. Simply supply & demand.  But this illustrates the point that there's a lot of stuff as of yet undiscovered out there.

Kevin