Answer:
Fine Art: The answer depends on who took the photograph, how collectible that photographer's work is, the quality or appeal of the image, where the image is purchased, the size of the reproduction, the number reproduced, whether the print is an original, one-off, limited edition or open edition, whether it's signed. You could pay less than $100 or tens of thousands of dollars, or more.
For other types of professional photography (portraits, sports, commercial, stock, etc.), there are too many variables to answer the question succinctly. You can find entire books devoted to the topic (see Related Links).