Why don't you have a shopping cart?
We don't currently use a shopping cart as we've found most designers looking for resources prefer a quicker purchase process. However, we do have a Collections feature that allows you to assemble the items you may want to buy in one place. Each purchase is a separate transaction, but after the first one, your card data will be saved so you don't have to re-enter it each time. You can also delete your card info any time you want.