There are 4 non-combat pets you can get from the item Mysterious Egg, Tickbird Hatchling, White Tickbird Hatchling, Proto-Drake Whelp, and Cobra Hatchling.
These pets do not appear under the pets category in the AH so unless the person knows specifically to look for them they won't find them by just searching pets.
On my server all but the proto pet sell for under 50g on the AH so they are pretty inexpensive for me.
What I do is several times a day post in trade "WTS -Insert Petname Here-, PST." switching it up every time and ask for around 150g each pet. When someone wants to buy one from me i simply buy the cheapest one off the AH and give it to them for my extremely jacked up price.
I've been doing this for several weeks and made quite a bit of gold off of it.
Tips:
Sell different pets at different times of the day. A good example would be to sell the Cobra Hatchling from 12-3 and then a different pet from 3-6 and so on so people assume you're failing at selling the item and you don't draw too much attention.
Deffinately sell from a bank toon, once someone finds out they're gunna be pissed.
Edit: Yes this is basically buy low and sell high and is more of a tip than a guide.
Cheers!