There is only a single location players are able to purchase Limes in Bulk and that is from Shelp who is located in Blazeridge Steppes. 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 only place to purchase Limes in Bulk is from Shelp in eastern Blazeridge Steppes. He is about as far east as you can go by Degun Shun. A picture of his location on the map can be found below.