We tried to start one in Lake county, but it kind of fizzled out.
Some of the first questions that need to be asked are mutual support for what? Natural disaster (flood, tornado, blizzard), personal disaster (house fire), total end of society?
Next, what do you want out of it/ what are you putting in to it?
How is it going to be organized? Who will be included? More importantly for some scenarios, who will be excluded? What geographic area are you looking at?