Go look up one of James Hamilton's talks, he breaks down the cost of running datacenters/cloud. 'Servers' are ~50% of the cost, hard drives are of course less t

Go look up one of James Hamilton's talks, he breaks down the cost of running datacenters/cloud. 'Servers' are ~50% of the cost, hard drives are of course less than 100% of server costs. So you need to at least double the cost of the hard drive. Tripling the cost of hard drives might be a good assumption for S3/Glacier because you could assume they are building servers where hard drives make up 2/3 the cost of the server.