I have recently been playing around with Fennux, which is another breedable. They have an awsome feature; when you set them for sale, they will show up on a online market where they can be sorted by traits. At the bottom you will find a teleport link to the place where the breedable is set for sale, so that secondary markets are still necessary. And it makes shopping so much easier!
See what I mean here:
Fennux Market
Online Marketplace 
