Possible SMOFcamp

I am thinking about possibly starting a four-times-a-year SMOFcamp for all of fandom and hackerdom to work, brainstorm, and connect using the Open Spaces method.

First step in planning is hard numbers on what it would cost. I would like to rent a hall, and seek a good location equidistant between Washtenaw County and Macomb County, for a reasonable price. Can you give me recommendations?