I love the Kindle, but...

So, what the heck is up with e-books costing different amounts of money? I can understand printed books costing more. I mean paper costs money so I can understand trade paperbacks costing more than mass markets, hardcover books costing even more, etc. E-books don't work like that, it's all digital. No matter how big the book is or how new it is, it shouldn't cost more than about $7.99. That's right, I said it and I'm even setting the price!