I concur with Susan.  Feasibility studies are an important step in
building the case for raising funds.  Generally, the costs are trivial
in comparison to the campaign.  The perspective from an outside
consultant or firm is important and enlightening.  As Susan pointed out,
the governing body may well be more likely to listen to an outsider than
the the staff.  However, choose your firm or consultant through a
selection process if at all possible.  They may not be familiar with
museums, their missions, their activities, etc....In addition, you need
a fair assessment, not an assessment that is predetermined.  Read
between the lines a bit here.  I will say that we used a feasibility
firm to our advantage in raising funds for a new museum facility (see
progress at www.omnh.ou.edu).  The study also was part of our overall
business plan (see posted request).