In our introductory comparative politics we often talk about purchasing power parity, to get the students familiar with the idea that costs from one country to another can't simply be expressed in terms of currency, but buying power. So the equivalent of a hundred dollars goes a lot further in Xian than Oslo.
The same is true about the US, of course, which any of us know if we've moved from from one part of the country to another. Salaries might go up but so do housing prices, or the opposite.
The New York Times has a good salary calculator for anyone wondering about the relative costs of various locales. For example, I plugged in Tacoma and Flagstaff, where I taught some years ago. It showed that not only were salaries lower in Flagstaff, but the cost of living higher than here. So it's a double hit.
A useful tool if you're thinking about relocating--find it here by going to the "Cost of Living Calculator".
