I think the situation might be a little different in the USA compared to Europe; however, Cephalotus are becoming quite common nowadays. Even the traditionally 'rare' clones such as 'Hummer's Giant' are quite common and thus the value has depreciated significantly. There are still a few exceptions, such as 'Eden Black'. Recently a couple of small examples (immature pitchers) of sister to Eden Black, aka "Tank Ceph 2" have sold for £123.88 and £255.00 on eBay UK but even this is relatively cheap for a rare clone. However, as others have mentioned, a plant should not be judged on its monitory value. Some 'rare' plants are also beautiful, such as 'Eden Black' but others are not that special and are simply expensive due to there rarity. Personally, I don't derive any more pleasure from my 'Hummer's Giant' than I do from my mature 'typical' Cephalotus but size for size I know which one would fetch the highest selling price.