Currently, most wolves aren't really worth a lot - as anyone who's glanced at the flea market knows. That makes sense, we only have so much den space and some wolves just aren't gonna make the cut. I'm sure this will improve as the site grows and there are more people buying wolves, but I think something that would really help is incentivizing players to release wolves. At least for me, the rewards for releasing wolves aren't really worth the hassle of leveling them up, and even though the wolves are the main draw of the site, most typical wolves are next to worthless. I could make money by buying cheap wolves and training them to release, but leveling is slow and the pebble reward isn't really enough of a draw on its own.
My idea - an occasional chance of receiving a moonstone (or even moonstone shards, but preferably moonstones) when releasing wolves. The chance might be higher the higher the wolf's level. This would automatically raise the value of even the ugliest color combinations as they still have the same chance of getting you a moonstone upon release, and it introduces a new way for moonstones to be generated into the economy.