The Consulting Rate Estimator allows you to weigh the differences of the cost of living for the locations your considering working. It's based on the government GSA Per Diem Rates and has over 600 U.S. locations to determine your break-even hourly rate and adjust your consulting rate accordingly.
You can also use it to easily determine your target market locations.
All you have to do is enter the lowest rate you would accept in the tool and it does the calculations for you. You can also estimate your rate by entering your weekly travel expenses. (Excel is required to use this tool.)