When the reward for 600th pet was added before WOD launched I was at 599, and the only pet I could get to hit 600 was Lil' Bling
, for a few weeks I tried everyday for him on 3 accounts (my 2 and my daughters). I didn't want to pay some crazy amount for him so I just tried daily. I got Bling on the weekend before WOD launched and thus the achievement. I really thought for sure that WoD would release before I got him.
Funny at the moment I find myself right at 699. The Bone Serpent is the only 6.1 pet I have yet to get and my most reasonable pet to obtain.
What follows is a basic list of of the pets I don't believe I will ever obtain:
Stunted Direhorn is only at 31/250 and hasn't budged in months, my feeling is that pet will be considered unobtainable at this point. (my hope is they change it to 250 battles not Wins) I find Pet PVP absolutely maddening and a greater time killer than fishing.
Those that cost thousands in real money, such as Vanilla WoW Collectors Edition pets and Mini Tyrael.
Or simply just no longer available, I'm looking at you Vampiric Batling
, and a couple of the Anniversary pets.
There were a few years in the middle I didn't play at all, and almost never got collectors versions when I did buy them. For me the collectors versions are fairly useless other than the pet, I have a few that all that I broke the seal for was to get the code to activate it on my account and get the pet.