There’s an NPC in San d’Oria that sells ceramic pots for 595, he’s at the FAR west gate (not the normal west gate.) He’s all by himself and does not look like he sells anything but he does :)
I heard there an NPC or shop in Jeuno that also sells pots but I have not found him/her/It yet :(
I don’t know of any other places then that sorry :(