Earlier quoted context omitted.
Hosting a static file in S3 you have to point people to manually find and download themselves is much cheaper because you don't have the built in captive audience, WhisperNet and everything else which comes with the Kindle ecosystem, so comparing the two only via a flat dollar cost is naive.
It's ridiculous to include the cost of the entire "Kindle ecosystem" with a fee called "delivery fee" - as other posts have mentioned, this is what commission is for. WhisperNet is another story - this is legitimately a part of the delivery - however, it's just 3G service that they leased from AT&T, and to assume it costs them even close to $2.58 per delivery is just ignorant. If I downloaded an 18MB e-mail attachmen…
If I downloaded an 18MB email attachment over 3g on my phone, while in the US, it will cost me $315.