At some point in your pet collecting career, it's best just to give up and admit you're obsessed. When Lil' Game Hunter went live with 3.0.8, I started looking at my options to get to 75 pets. Most people shouldn't have too much difficulty reaching 50 (Shop Smart, Shop Pet...Smart), but 75 is a little unnerving. I don't have any of the Collector's Edition, Trading Card Game, or fan event pets, and I also play Horde. That leaves me without access to the Sprite Darter Hatchling, and on a lot of realms also makes it harder and more expensive to get the White Kitten, on top of being more expensive to get the lion's share of the faction-specific pets (which, naturellement, are Alliance). What's up with the Horde and pet hate? Sheesh.
So that was somewhat worrying, and I approach this achievement with one question in mind: is it possible to do this without having dropped money on CE, TCG, or event pets?