http://blog.ipublishcentral.com/category/authors/ishani/
“Amazon was buying eBooks from publisher for about $13 and selling the same eBook, at a loss-leader pricing, for $ 9.99 for reading on its Kindle eReader device.”
This is consistent with what I’ve read elsewhere.
They did do that for a period, hoping to drive the price down from the publishers when they first colluded with each other, but not for long. Other wise they would have dropped e books.