A lot of what an employer will be willing to pay is based on YOU as a person and your skill set.
An interview will allow you to tell them all about your stengths, what you can bring as an employee and how you will fit into the environment of their office. Without that chance for them to find out about you, I would think they might lowball the salary, especially considering they most likely have many other resumes for that same exact job.
When I interviewed for a position recently, the HR person asked about halfway through the interview what my salary requirements were (and a good deal of resumes I sent out for other jobs <i>required</i> a salary history attached). I told her what I was making previously and thought it would be 'in that ballpark based on other job benefits'. She then told me what the range was and I was smack in the middle. It still gives me a chance to work the salary a little more, and gives her an idea what it would cost to hire me.
With the job market so tight right now everywhere, I would say you need to make the investment in time for the interview, and if it doesn't work out it doesn't.
On lewski709's comment about hiring and 'honesty up front'. Yes, you need to be honest, but that can come after you see if it's a fit. After all, you may do the interview and just LOVE the spot and might be willing to make a cut, or they might like you so much they are willing to pay a little more than what they thought. You will never know that unless you go and talk with them.
And if it doesn't work out, think of it as good practice for the next one that will.
