When doing searches for egglings for sale, they will only show up for Fabled Species. However, when doing a search for egglings of 'Any' species it's clear that there are loads of eggs 'for sale' (108 ATM). At first I thought they were all found mystery eggs, but opening the first five eggs' profiles revealed them all to be Lunemaras. So I did a double check and searched for Lunemara eggs for sale and got "There were no results found." Again this only seems to apply to regular species since searches for Aeridini, Griffi, and Lighira eggs all returned results.