(Micah Baldwin) Just three months after Amazon tied up its bevy of contracts with top publishing houses, it looks like those deals might not be working out well for several companies, as they’ve reported declining e-book revenues in recent months. The Wall Street Journal reports that Hachette, HarperCollins and Simon & Schuster have all reported declining online book sales after inking deals with Amazon that gave the publishers more say in the prices for their titles. A look at the Kindle store found that each of the five big publishers – which also includes Penguin Random House and Macmillian – have an average cost of $10.81 per e-book, while online books from others had an average price of $4.95, research group Codex Group LLC found. “Since book buyers expect the price of a Kindle e-book to be well under $9, once you get to over $10 consumers start to say, ‘Let me think about that,’” Codex CEO Peter Hildick-Smith tells the WSJ. The group found that in some cases the cost of an e-book was actually on par with the cost of a new hardcover version.