There is only a single location where you're able to buy Chickpeas in Bulk and that is from Naknar who is an NPC in Iron Marches. 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.
Naknar is located west of Grostogg Kraal Waypoint in northeastern Iron Marches. It's the northeastern most Renown Heart in the zone so it shouldn't be too hard to find her.