But one thing: the Physical Quality. It's nice to have a hard cover color book, with great full page art and pretty sigils on every page....but if your just going to use that as an excuise to jack the price of the book up to $40...then don't bother. I'd much rather have plain black and white text and no art for $15.
The full color art and high production values of a given book isn't usually an excuse to jack the price up, in fact if publishers could put out a full color book for the same price as a B/W book, they'd all do it.
It's usually the other way around. Publishers want to put out a high quality book, but when the find out the cost to produce a full color hardback with any volume - it end's up needing a $40 cover price.
For example, some time this year, I'll be releasing a hard cover setting handbook for my
Kaidan: a Japanese Ghost Story setting. I've had the goal of maintaining high production values in the adventures and supplements - by getting top quality artists for cover and interior illustrations, (I'm a top-end fantasy cartographer so they all have killer maps), and I did the page layout myself to insure a top quality looking books are designed. Most of our products have been PDF releases only - all with full color art and maps. Now that I'm looking at a hard cover, the costs are starting to point out that I might be only able to release a hard cover as a B/W only book.
All my maps and illustrations so far are all full color, but that doesn't matter, the costs for printing a full color hard back is exhorbitant - it might take a patronage (Kickstarter) to fund a full color book.
If publishers could produce full color books that were clearly affordable, we'd do it everytime. Making a book full color is not an excuse to drive the price of the book up - that's just silly. All the extra costs are profits for the printer, not the publisher.