Save money on shipping costs when you purchase multiple books on the same invoice. All you have to do is add the books you want to your eBay cart. When you are done shopping, you can complete the checkout process through PayPal and make one payment for all the books together and one combined shipping amount. The shipping discount will automatically be applied to the order total for multiple purchases if they are paid for together. Once payment is made, your order will ship within 24 hours.