There are three different locations for you to purchase Kidney Beans in Bulk. These three locations are Snowden Drifts, Diessa Plateau and Lornar's Pass. Now before I get started with telling you the two locations keep in mind in order to purchase any goods from a Karma vendor you must first complete the quest they have for you. That is of course if they have a quest available if not you'll be able to buy whatever they're selling right away.
The first of these locations I will go over is Diessa Plateau. The Renown Heart Vendor is just south of Nageling Waypoint is who you will want to visit. Nageling Waypoint is in the southern portion of Diessa Plateau almost smack dab in the center of the zone.
The second location to buy Kidney Beans is in northern Lornar's Pass right next to the zoneline of Lornar's Pass and Snowden Drifts. The closest Waypoint is Thunderhorns Waypoint.
The third and final location to buy Kidney Beans is in Snowden Drifts in the northwestern part of the zone. The closest Waypoint is Seraph Outriders' Waypoint.