i don't have a pob, but i'm a customer. some already were listed, but i can add at least two more that despite not being on mining system, most of the times they have some ores, not always at a best price, but since they may be at the midle of the route, the profit is still very good. so there is one on honshu that have several ores, and another on omega 55 also with several ores.
edit:there is one on Nu, not far from Roratonga that the last time i visted i remember see some azurite, if i'm not mistaken.