There is no way that the average purchase costs $2.50+ to deliver, even amortized over the lifetime of the book.

Amazon can charge whatever they want; I just think they should be transparent about what people's net pay will be. It's disingenuous to advertise that you take a 30% cut plus "delivery costs," and then mark up the "delivery costs" to over 25% of the average book price. Apple uses a similar paradigm (processing fees do not come from their 30%), but they only deduct the actual processing fees.