I'm just gonna toss this out here for US folks: Embrace your Brazilian Overlords. I spent a couple days on a low pop Brazilian server and got the 3 breeds that I wanted (not rare...still had to stone). I saw a lot of minfernals during those couple of days. Just make a DK. Lots of resources out there for finding which realms are low pop.
Carry Pet Experience Reference Guide: http://www.warcraftpets.com/community/forum/viewtopic.php?f=10&t=8829