Andrew Hyde learned that it's very, very high:
Use Amazon to run your website: .01 to download a file. Use Amazon to sell your book: $2.58 per download + 30% of whatever you sell. Amazon’s markup of digital delivery to indie authors is ~129,000%.
Kelly Burdick does more math:
Amazon’s total fees ate away almost a third of Hyde’s royalty: The book retails on Amazon for $9.99, and under the 70% percent royalty plan Hyde imagined he would get $7. But Amazon charges $2.58 per download to deliver the ebook, with the author’s royalty being calculated on what’s left after the delivery fee is deducted.
More on the tyranny of Amazon in publishing here. Regarding the Dish's first self-published book, The View From Your Window, Blurb's print-on-demand price for a soft-cover version has regrettably gone up 33% since we launched it in late 2009. But we now offer it to you with no markup from us.