Astral Orb or Astral Hanzo Orb quest - 4020
You can't turn it in without the actual pet, but it loads perfectly fine on Carbon. As does the Crimson Orb quest, but same issue.
As for buying the pets, since Nulgath's Birthday Shop is updated since their release, you can't. Like Quibble Coinbiter's shop - you can't load past versions.