Why a dearth of some brands on the used market?

Hi All - 

I’ve been looking for some of the higher end Cardas power cables on the used market for the past few months. I’ve been pretty surprised how rarely I see them come up for sale. On the other hand, I’ve seen some brands being sold at a much higher frequency. I’ve also noticed that the less expensive Purist stuff seems to also almost never come up… 

I realize the above is a broad blanket statement, so I’ll repose it this way. What are you all looking for, seemingly in vain (or so it seems from the wait time!), for a used item to come up in your desired price range?