"The reason that Cloudflare can pull this off is the same reason why S3’s margins are so extraordinary: bandwidth is a fixed cost, not a marginal one. To take the most simplified example possible, if I were to have two computers connected by a cable, the cost of bandwidth is however much I paid for the cable; once connected I can transmit as much data as I would like for free — in either direction.

That’s not quite right, of course: I am constrained by the capacity of the cable; to support more data transfer I would have to install a higher capacity cable, or more of them. What, though, if I already had built a worldwide network of cables for my initial core business of protecting websites from distributed denial-of-service attacks and offering a content delivery network, the value of which was such that ISPs everywhere gave me space in their facilities to place my servers? Well, then I would have massive amounts of bandwidth already in place, the use of which has zero marginal costs, and oh-by-the-way locations close to end users to stick a whole bunch of hard drives."

Backblaze, an online storage and backup company, is also a member. They charge $.005/GB/month for S3 compatible storage. And if you map and access a bucket through Cloudflare there is no egress fee.

So it's possible to store and access your files at 1/3 the price of Cloudflare alone by using Cloudflare (plus Backblaze).