Ask a Manager has a great posting about how to answer the all important question about your salary requirements. I like her advice, and I think I offer additional good advice in the comment I left on the posting:
"I think many folks get scared of the salary question because it feels so very personal (most of us have hangups/issues with money, right?). That's why the key here is to treat it like a business question rather than a personal question. I am in favor of Ask A Manager's point that the candidate should do some research. With the salary calculator on hotjobs.com you can get a pretty reasonable range for most jobs. Then when the salary question comes up you're not answering personally about your own finances, but you are able to say something like, "Based on my market research, positions at this level in this industry, with this scope of responsibility typically pay between $XX and $XX and that range is acceptable to me." Then follow up with a business question: "Is that within the range you have priced the job at?" If you've done your research and your price range is accurate, they will be impressed! If they get cagey with you about their range and aren't forthcoming, you are going to learn a LOT about whether you really want to work there or not!"
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