complete Prince Wakanga O’Tamu told you one of his primary sources for buying magic items had been a Red Wizard named Ozymandius. Unfortunately, he was only in Port Nyanzaru for a few weeks before being sent off on a expedition by his superiors. He let it slip that the destination was The Lost City of Mezero, and that the expedition was being done without the blessing of the Flaming Fist.
If you can find him, perhaps he can sell you some of his goods and point you to other people who may sell even better stuff.
Why are The Red Wizards of Thay interested in Chult and The Lost City of Mezero?