All printed book prices are set by market will and demand and have almost no basis in actual costs. Like every other retail business, the goal is to get people to spend as much as you can. So you do things to make people think the value is higher, for example, you use a harder cover even though the cost of printing it is negligibly higher than, say, a trade paperback. Even the shipping is not much more, as third parties are used to perform recycling tasks, rather than shipping the books back to the producers.
So here comes eBooks and you have myriad interpretations for their value. The publishers have ignored them for so long that they basically lost their opportunity to tutor the public on how much they should think an eBook is worth. Now you have the pirate camps that think bits are worth nothing, the entitlement morons who think they are somehow owed some special deal because it's easy to make a file copy, or whatever backwards logic they present. You have the "I hate DRM it's always evil" camp which is a bit extreme but not entirely baseless. And then you have the more positive groups like those of us, you and I, who value the benefits beyond any of the negative aspects of what's available currently.
Then you have to take into consideration the difference between people who place value based on the product they hold in hand vs. those who value a product like a book or movie based on their opinion of the creators. I find that too many people have lost their connection to the creative minds behind these works they enjoy and that only complicates the matter further. Consumers feel they are entitled to the opportunity to buy new books, as though they are a commodity that can be produced at will regardless of who is on the other end doing the work. It's pretty insane.
Finally, take into consideration other forms of entertainment that are vastly more transient and still cost nearly as much money as a book. For example, a movie ticket, depending on where you live, will cost $10. That's one viewing, in a large room full of loud smelly rude people, and you might not even like the movie. In the best case scenario you got about 3 hours of entertainment for $10 and that's it, nothing to sell, or trade or lend, or anything. Why, then, is more expected from $10 paid for reading materials? Why should a book be a product that one has ownership of, if it is offered sufficiently cheaply?
Well prior to recent times, there was little choice on part of the publishers of books for the terms of a sale. They basically had to sell their works printed on paper and it was pretty final. Now things have changed, technology makes it more practical to set different terms. This makes people quite angry, as though they have some unwritten guarantee of terms in any contract or offer between themselves and a corporation.
Regardless of how you feel about these changes, they do also complicate the pricing and value perception questions.
So ... how could you ever expect people to agree on what a good price is then? haha, really I think that the consumer and the producer need to be more tightly linked for the market to correctly work out the truly accepted value for eBooks. So this recent hullabaloo between macmillan and amazon will help achieve that connection. The same goes for Apple's business model with the app store and the upcoming iBookstore. They properly place themselves into the role of distribution chain without concern for what is being distributed. By taking a flat predictable fee and letting the producer of the content set the price, the conversation is made between the rights-holders and the consumers more directly. I think over time, as more outlets take on this role and use this pricing structure, a more agreeable eBook market will emerge and all in all, pricing will feel fair, and eventually we'll see a consensus on value.
Of course, the regulars here will still bemoan the fact that they have to pay more than zero dollars for anything, ever, but that's the internet for you.