That's not exactly how this works. The flat sale has been over for a bit now, so the only way you could buy a pet prior to the next event is by purchasing a custom. At the moment, I believe the only custom slots open are bribe slots, which cost a set of the current contribution items. If you're interested in purchasing one of these, please fill out the custom form and post it.

Also, certed is on the certificate, where as uncerted is just the image of the pet.