Amazon was relatively inexpensive when they offered DHL World Mail shipping option. That must have been 2-3 years ago. It was around 1300 yen per shipment plus 300 yen per item. The packages would be delivered in about 3-5 days instead of EMS's 2-3 days. Now they only offer EMS at the rate mjm listed above.

Air Mail and SAL shipping are much less expensive, but online stores avoid them because they don't offer delivery confirmation. Without confirmation, some buyers can easily repudiate the receipt of the package and request a refund with the vendors or charge back through their credit cards.