Some have probably already noticed this, but...
This is for anyone, like me, that pocrastinates on leveling pets. A lot of the secondary pets in WoD are not WoD zone pets. They are duplicates of Azerothian pets. But, they are level 23-25 pets. So, keep an eye out for rares that you might already have, but are lower levels. I have managed to upgrade half a dozen or so pets this way.
Happy Hunting!