Vanity Pets have long been a nice seller on the Auction House. You could take your faction pets and sell them on the neutral AH to the Horde and vice versa. Some of the very rare pets for for a nice chunk of change. For example, the protodrake whelp is going for over 500 gold on my server, while the other rare pets (whelplings, ooze, etc.) are going for several thousand.
With the addition of the Argent Tournament, this is you opportunity to get into the pet scalping business. I have found very few of these pets on the AH and they must be going quickly as they are not up for that long. The prices I have seen have ranged anywhere from 4.5k to 6k gold. You can basically get a pet if you do the dailies for 8 days in a row. If you have multiple character doing it, all the better.
Now is the time to get in on this market. These should be in high demand for a bit as collectors will be busy buying pets for themselves, not to mention the mounts, banners, and tabards.
Have any of you sold these pets?