There's a huge disparity in the cost of living in various parts of the US. For example in California and New York the cost of housing can be nearly twice as much as it is in smaller states. We are paying less (by twofold) for our 3-bedroom house in New England than I paid for a one-bedroom apt in New York when I lived there nearly ten years ago. Some states have a much higher sales tax than others while some states have no sales tax and an increased income tax to make up for it. CNN's Money Magazine did a comparison of states not too long ago. Here's the link to the article:
http://money.cnn.com/magazines/moneymag/bplive/2006/index.html