It would be useful for people to look at a site like this.
http://www.charityvillage.com/cvnet/career_centre.aspx
Not all of the jobs post salaries, but a number of them do. I've been watching the site (and similar ones) closely for while, and can tell you this for sure - most of the management jobs (organization, delivery of services, direction of staff) come with salaries in the 50-65k range. Entry level positions (contact management, fund development, etc) are in the 35-40k range.
In my experience, this would be ~2/3 of the wage paid in the private sector. I would really like my next career to be public-service oriented, but I would (VERY) likely have to take at 20-30k pay cut to do so.