Yes, members and non-members alike can purchase potions, scrolls, and food items.
When you first get to the Shark Tooth Island, there is a guy giving out milk. Get milk and then go over to the guy giving out grass skirts. Get a grass skirt, go over to the ancient ruins and jump on...
Ingredients.
A potion is a mixture of ingredients which is thought to achieve a specific effect though the use of magik.
They are liquids that are intended to be drunk. It is often claimed that they have magical, medicinal or poisonous characteristics.