some time ago I found a very nice website that tracks prices of some, maybe all tcg mounts and pets, across all realms. Cheapest to most expensive and so. But I didn't put it to the bookmarks and forgot the name, I was wondering, does anyone know?
I think AHSpy used to allow that but it was shut down. Undermine Journal works per realm but obviously not what you are looking for. Sorry I couldn't help.