You have to have Marine Mania for this trick. Click on any animal in Zookeeper Reccomendations in a campaign where you aren't allowed to buy animals(Smuggling Ring Exposed, for example), and you will be taken to the Adoption screen and there will be animals to buy. However, always feed the animals from Zookeeper Recs. because it will go off if you go to Shelters, Animal Enrichment, or Food. If you do do this you can always repeat the step(lol).