Regarding pricing, I set my price (roughly) on the expected to effort to create a map, based on my experience.
For a single monochrome/greyscale novel style regional map in trade size at 300DPI, ready for print I would typically ask around $XXX. I would retain copyright of the image and retain the right to display it in my portfolio (printed or online). You would have a limited license to use the map in any version of the novel/series or for any related promotional purposes. (This really means that if you wanted to use it in some other form, say for example selling posters of the map, or in a board game, additional terms would be required.) This price also includes one significant client initiated re-work.
As I said, this estimate is based on my expected effort, and can vary up or down depending on a number of factors:
The amount of geographic detail in the map
The number of labeled places in the map
Detail of place icons (i.e. dots vs. little pictures for city markers)
Whether the mountains are all hand drawn or can be "stamped" from a limited set
If you have any specific fonts in mind that would require I purchase a font for which I do not already have a license
The number of maps in the style (I do bulk discounts as artwork can often be re-used)
The amount of "chrome" (details such as flourishes, iconography, special fancy graphic borders, etc.)
In general, the more details you can provide the easier it is for me to construct the map. Ideally, a rough sketch of the geography, all of the place labels desired, information on the theme desired, and any other details. (Often I get provided snippets from the novelist where they are describing locations to understand the atmosphere).