I don't believe this is in any way going to turn into a situation that equates to Blizzard selling in-game currency. Lets define two parties:

Buyer - a player that might potentially purchase the pet from another player in-game, either directly or through the auction house.

Seller - a player trying to sell the pet once they obtain one, either by purchasing or getting one as a gift.

Supply will be infinite, and the barrier to entry is very low. Demand will be low because it will be stupid easy to obtain the pet, so everybody who wants one will probably get one quickly either by buying it themselves or getting them as gifts. The value on the auction house will end up being very low because the time it takes to make a significant amount of in-game gold is more valuable than the $10 the pet costs.

Essentially, if I'm a seller, I need to make a pretty large amount of gold to justify spending my $10 of real money. Probably well over 1000 gold. As a buyer, my time is valuable to me, so I would rather just spend 10 bucks and not waste the time it's going to take farming the gold. That simple fact will create a situation in which the seller will want a big chunk of gold for giving up real currency, but the buyer won't pay it because the time it takes to make that gold outweighs the value of just dropping 10 bucks real quick.

Additionally, if anybody is worried about people using the cubs as a legitimate exchange medium for buying gold from gold farmers, I don't think having to spend an additional $10 on the pet will be attractive, and the gold sellers aren't going to give you a price break just to help you save risk.

To summarize, the rules of supply and demand, and the real money component required to obtain the cub will ultimately remove any possibility of using it for meaningful in-game profit.