The heirloom tribe is sold in the thieves' area of undercity, and it is sold in the Explorers' Hall of Ironforge Castle in the League. It costs about 500 gold coins, and levels 60, 60 to 90, and 90 to 100 need to be upgraded. All walks of life have heirlooms, and there are many kinds of heirlooms. You can click on the favorites menu next to the main menu to view them. If possible, I can add your friends and give you some family heirlooms, but family heirlooms can't be upgraded until level 60.