My idea is that for 50,000 gold or 1000 crowns (or something like that), players should be given 1 pet talent exchange of their choice. Essentially they would pay and be given credit for 1 exchange, they could make the exchange on either side of their pet talent sheet and they could see every pet talent that their pet has available to it upon making the exchange.
If a player wanted to exchange every stat on both sides, that would be 8 total talent exchanges which would cost 400,000 gold or 8000 crowns. Assuming a pet is about average and randomly gets 2 acceptable talents on both sides, to make the pet into a perfect pet would then cost a player around 200,000 gold or 4000 crowns. If a player didn't care about racing, or didn't care about in game character playability (character play pets and racing play pets are typically two entirely different pets), then a perfect pet for character play would reasonably cost a player 100,000 gold or 2000 crowns. This is kind of in line with permanent mount costs, which is fair as pets are permanent pets and adds to every battle that is played.
Net result, people would play more at upper levels to raise gold, at lower levels people are more likely to pay crowns. Crowns is income to the game and so Wizard101 makes more money. All the time and effort players spend to train up a pet can also be worth the time as they can fix their favorite pets just the way they want them even if it takes awhile to raise the gold or takes a bit of money to do it through crowns.