I actually think Bronze Medals (and most common pet gear) can be sold in the Bazaar, you just need to be on the right page/tab in the Bazaar selling menu.
Felix Faucibus, up in behind the Morphing Pavilion, is who you want to go see to sell your unwanted pet gear. He sells some gear and buys the rest. He buys the No Auction valuable rare gear that can be obtained by doing certain pet training activities - the stuff worth 1,020 gold a piece.
Standing nearby you will find Galina Karus, who sells and buys snacks.
Why? Our training is ten times easier than Wiz training; we would have to take our pets off training to feed them ( and we can't cancel training ), we don't have crafting yet, and gold is easy to get. There is no benefit here in feeding unwanted gear to a pet.