So now you have over 50 Plat and you want to purchase the pack you say? Well that should be easy! Although there aren't any 50 Plat packs in my knowledge. Anyway, go to the store, go to "items", and whatever class you are warrior/enchantress/archer. Let's just say Mage for now, then tap "item-packs". Scroll down to whatever pack it is you want ^_^ remember, if there's another pack with the same name, they're a different level. Feel free to ask further if you're stuck

EDIT: scratch what I said, listen to the guy above me "Samhayne". He knows EVERYTHING about the game. I'm just "A-kid-down-the-block".