As an author, it's depressing to see empty books -- stickers and all -- selling for twice as much as full ones.
BTW, for those buying, unless you're a reporter, I highly recommend the large size. If you look at the notebooks of great men, most tend to be closer to the larger size. Michelson is the one that sticks in my mind, since I walked past those notebooks every day for 7 years.
However, while I do agree that Moleskine notebooks are absolutely gorgeous, I usually buy other types at about 1/3rd of the price.
Their diary/planner, however, is merely on the high price end for such things, not by a factor of three. And in the years I've used one of those (I use a much tinier planner now), I kept on being pleasantly surprised by their attention to detail in the design of tables, grids and bubbles you'd find in a planner, all of it really well-thought-out. But then, a pre-printed planner is not the same as an empty notebook.
I used to do that as well, and felt Moleskines were just too expensive. Then I splurged on one a couple of years ago, and never had that feeling again. Don't know if I just feel that I get my money's worth, or that my brain just simplistically adjusted to the price.
Empty pages is also my thing. In general I have four, pocket sized one, A5 sized main notebook, A4 sized sketchbook for drawing, and a reporter style watercolor pocket one (I love the panorama-like landscape format for pictures).