I have been struggling with pricing ever since I started selling books. I started by selling on Ebay so I was able to see how much people were willing to pay for my books by using the auction system where the buyers were setting the prices. I did that for over a year before I joined Etsy, so the auctions helped me get started with my Etsy pricing. And then when I thought I had it all set, the Canadian dollar shot up and become near par with the US dollar so I needed to adjust pricing again.
Otherwise, the main factors are the number of pages and the book's dimensions. So price increases as the size and number of pages increase. Because I think the paper is the most significant cost element for me. Some bindings require significantly more effort and time too, so that can also be a factor. But I try to be consistent at any rate. So if there are 2 books in my Etsy shop that look very similar in size and style then they are the same price even though some other factors might not jive. But I want it to be predictable for the buyers.
Recently another Etsy seller with handmade books asked me about pricing and it was hard to compare since her books were mostly hardcover books (check out her shop here: flurrsprite.etsy.com) I actually feel that fully casebound hardcover books should cost more than my leather journals. A hardcover book just has so much more time and effort in the cover with all the measuring, cutting, pasting, and drying time.
Actually when I first started trying to sell books on Ebay, they were all very traditional case bound hardcover books but nobody bought them. I watched the auctions for a while to see what people were buying and it was pretty obvious that leather books were rather popular. So I decided to try leather....and the leather sells. Since I've started selling on Etsy (Mar 9/07) I hadn't sold anything that wasn't leather until last week. But my books aren't very artsy either; I think they look good but they are usually plain, unembellished, etc. Artsy books that are well made should be higher priced too. Mine may have interesting or unusual bindings or whatever but they are not artsy.
So the hardcover case bound books and well-made artsy books should cost more, but I don't think most people are willing to pay what they are worth. First of all, I have found that when people buy a handmade book, they want it to look handmade. My traditional hardcover case bound books did not look handmade at all, and I even had some people question them thinking they had to be commercially manufactured! I think that makes it harder to get a good price for that type of book because the buyers think it looks the same as a book they can buy at W*lmart. So I try to keep my books looking handmade but still well made, of course. And I'm guessing that artsy books and artist's books typically don't fetch their real worth, as is the case with a lot of art.