There are several ways to figure this out. One would be to use the SVS Website itself and put the same sub in your shopping cart as if you were going to buy it. Then you would see what they charge for shipping.
Otherwise, it is most likely that the cheapest shipping method would be via FedEx Ground service. If you know the weight and measurements of the package(s)--hint: pull out the bathroom scale and tape measure--then they have a rate calculator.