There will be a modest item shop.. where you can purchase cosmetics. Nothing that will make you better than another player. For example, if you want a blue hellfire special ability. Every other player has the standard red hellfire, but if you want different colors you can get this in the item shop.
You'll still be able to craft gear without going to the item shop. There won't be anything you can't achieve with regular crafting and trading. Basically if you want the blue hellfire, you can buy the skin in the item shop, or you can craft the spell that makes it blue.