That the inherent 'cost' of an ebook is substantially less than that of a traditional book (no paper/printing cost, warehousing, shipping, stocking, distribution, handling, etc) makes me wonder what, besides Apple's profit, I'm really paying for by continuing to purchase content from the iBookstore. I doubt somehow that the actual author is getting more money for their work. Well, and some 'books' are not available through the Apple store.
Not only that, but the purchaser does not own the eBook she or he buys, they are merely leasing the rights to read it.