There are some important pet-related topics on the beta forums of which collectors and players in general should be aware. Blizzard is leaving the threads open so that the community can add their feedback and input, but let's remember to keep the discussions on these threads mature and constructive.
Cannot Trade/Sell Wild Pets
Blizzard announced a change to the trading and selling of wild pets in MoP. [source]
We just finished a pass making all pets that are caught via pet battles in the world non-tradeable. This means these pets cannot be put in cages for trading or posting on the AH. We felt that the option to buy these pets on the AH would take away from the exploration/collection gameplay of the system.
This could always change in a future patch, but this is how it will go out with MoP. You should see the change in our next build.
Keep in mind that this decision may not be final, and this might only be a temporary fix until a better solution is found and implemented.
Some Pets Upgraded In Quality
There are a number of non-wild pets that many would argue deserve a higher rarity quality. Blizzard has compiled a list of possible pets that will be upgraded to rare status, however this list is not yet final, and developers are welcoming feedback and suggestions on which pets should be added or removed from the list. [source]
Keeping the Discussion Going
For players who are not participating in the beta, and therefore unable to respond to the threads linked above, feel free to voice your thoughts and opinions on our WarcraftPets forums.
The change to the trade and sale of wild pets as well as the adjustment to non-wild pet qualities might not be set in stone yet, so let's continue to provide constructive feedback for developers, while keeping an open mind.
Trading Wild Pets Change and Pet Quality
July 23, 2012