Kamas are the currency of Amakna. They are earned for defeating enemies in combat, selling items and completing certain quests.
The symbol for kama is a fancily styled K. Any NPC or other game price using K means kama. The suffix 'k' means 1000 of something if it refers to an object. ('10k wheat' means 10,000 wheat.) When it refers to the currency, a k is used to represent normal units and a double k is used to indicate that the item price is --Thousand. For example, someone is buying a tofu feather for 20k. This means 20 kamas, whereas if he had said 20kk it would have meant 20,000 kamas.