I agree, Neogonodactylus. I'm not sure about the relative abundances of Wunderpus and Mimic - both are rare and hard to find, but perhaps since the behavior of Wunderpus is more predictable in the wild, they show up more often in the trade. This does not bode well for their future.
If you see one for sale, and feel (as we do) that these animals should not be sold, then talk with the supplier about this. Let him/her know that you will not buy the animal because it might put their populations at risk, and that you hope not to see one in that shop/website again.
The wild-caught octopus trade in the Indo-Pacific remains relatively unchecked. We should have the same concerns about all wild-caughts, not just Mimic and Wunderpus. The removal of one O.aculeatus male can disrupt their entire local mating system and we don't know what effect this can have on female fertility. Females are rare, and collectors do not sex them and let them go. O.bocki live deep in rocks and coral, and are likely collected with cyanide. Some may not be, but at this point we don't know. Bottom line- buy a bimac.