Shipping costs shown at time of checkout are only estimates. The program we use within our website calculates this cost. When your order is processed, we only charge the actual shipping cost. In most cases the charge shown when you check out may be correct when smaller items are purchased. However, in some cases we might find a way to more effeciently pack your order or combine items into a smaller package that our program might not see. This is typically true on shipping larger items such as gas tanks, bumpers, floor mats ect. On the smaller items we use the post office flat rate boxes that our program may not be aware of. Our goal is to save you money!