Probably most of the people on this listserv group hope to place a book
manuscript with a university press.  For them there is an interesting (and
dismaying) article in the most recent Perspectives by the new AHA president
Robert Darnton.  Although his focus is on monographic books, his most
startling statistic concerns an editorial series.  The first volume of the
papers of Benjamin Franklin sold over 8000 copies, the most recent upteenth
volume a few hundred.  Understandably academic presses are shifting much of
their lists to more salable titles and away from specialized monographs.
Even when they get good reviews, they don't sell enough copies to meet
costs.  Darnton plans to recommend electronic publication as a partial
solution.