1. A method for weight based upselling, the method comprising: receiving a purchase request for an item from a customer; determining a weight of the item; identifying, in dependence upon the weight of the item, a shipping weight range and a shipping cost for the item, wherein the shipping weight range includes a maximum shipping weight; calculating a difference between the weight of the item and the maximum shipping weight in the shipping weight range; selecting an upsell item in dependence upon the difference between the weight of the item and the maximum shipping weight in the shipping weight range; and offering the upsell item to the customer, including offering to ship both the item and the upsell item for only the identified shipping cost.