Here is an interesting link where you can type in how much you make, where you live now, and where you are going to move to. It will then tell you how much you will have to make in order to maintain the same standard of living you have now.
http://www.bestplaces.net/col/col.aspx
For example, someone making $60,000 where I live now (Orange County, CA) could live on $39,659 in Des Moines, IA and have the same standard of living.