I was not previously aware that every unit of transfer increased the cost of the hosting services. It makes more sense now. But if so few people need repeat downloads, why is it such a concern? According to the price structures at http://aws.amazon.com/s3/pricing/, data transfer is billed on a per-gigabyte basis, unlike more conventional web hosting which has a tiered pricing structure. If 1% of customers who have bought RealScenery scenery products re-downloaded their purchased scenery, how much extra would it cost?