Don't forget that the Stone of Destiny leaves the store soon! With the maintenance of September 26, 2012, this item will cease to be available for purchase. Be sure to buy yours before then!
Remember, you can purchase the Stone of Destiny now even if you are not yet Awakened; you can save it in your inventory or on the Dimensional Merchant until you are ready to use it and Awaken your main class or Dual Class as the class you really want!
Find this item in the in-game L2 Store, or on the website's L2 Galleria.