I saw something yesterday that made me do a bit of a double take. I am a pet collector. My fiancee is also collecting pets. She has been stuck at 47 pets for a bit now and only needed three pets to hit the 50 mark. For months I have checked the auction house for Oracle pets. Apparently, searching the pet tab will not locate these pets. If you do a manual search for them, you will be surprised at how many you find!
Last night I did a manual search and found at least two of each pet, which I promptly bought. I sent the pets wrapped in blue wrapping paper to my fiancee. When she got home, she was SOOOOOO excited. She finally got her stinker.
I think that there is a nice margin for profit on these pets. I am sure that most people do not know that these pets will not show up in the pet tab. You can check the auction house for what oracle pets are available, then spam in trade chat that you are selling them for 3-4 times what you saw on the AH (dont tell them this of course, just spam the amount). I bought most of the pets for under 10 gold, except the Proto Drake Whelp which I paid about 175 for. I imagine you could pull in some nice cash this way. If someone whispers you, snatch the item off the AH and sell it to them at the inflated price!
So, from a fellow pet collector and entrepreneur, I hope this helps you out.