Before spending x ammount on this, you might check the NPC in Jeuno that sells this item. Often you can get items from NPC's for = or less than AH prices, so buy smart.
Goblin Shamans in Lower Delkfutt's Tower and in Sauromugue Champaign drop these, though I've found the drop rate horrible but I didn't have Thief subbed. Hope this helps.