Books and printed materials are of course neither a single category nor a single form. Categories, history and fiction two examples, are different and their dealers’ experiences different. Forms as well differ. Important broadsides continue to rise. Manuscript material does well if not so well as years ago when the very wealthy routinely paid nosebleed prices. These obsessed collectors have now moved on, the remaining high-end players long-term investors by default because they dare not sell for fear the rooms become their abattoirs.
There are also wide ranges in price. Some dealers consider nothing less than $10,000 and others nothing more than $100. A few years ago an inventory of almost 100,000 books was sold in Kingston, New York at auction for $1,000. Last year George Washington’s personal copy of Acts passed at a Congress  brought $9,826,500 at Christie's. Both lots live inside the world of books but live on different continents. The widely held belief is that valuable material now dramatically outperforms and the evidence broadly confirms. Most dealer material however is more pedestrian and it is difficult to accept that what we thought was special is not judged that way in the marketplace anymore.
The dividing line between the secure and probably rising and the weak and probably falling is a number but not a gauge. That dividing line 6 or 7 years ago was about $1,000 and has been steadily rising since - today around $2,500. Such prices levels are only perceptions. A Poughkeepsie item that cost $2,500 would be a big deal, a Lincoln letter at that price ridiculously cheap.
The better way to think about price is whether, at the price posted it sells. By that measure a great deal of material is overpriced. But if there are marketing approaches that have not yet been used they should be employed before prices are adjusted. Only after other alternatives have been considered does the question become whether it is appropriate to bring the price down to the level where it transacts. That is often painful; at some level an admission of defeat and isn’t necessarily going to work.
How dealers approach such questions depends on what they sell as well as what their personal situations dictate. Age and experience, location, financial resources, and specialties all matter, the only constant today change, the best solution for many adjustment both because it takes time to sell and because the trends may continue to be unfavorable for some time. But if changing, how? Is it changing how we sell or is it changing the price? It’s probably both.