As for determining my own value, I worked for a lot of cheap companies early on and am still trying to compensate for that. It's all about guessing the right number with no actual data, which is a pain. If I knew that all programmers made $x per year, I would ask for $x plus a small premium (because let's face it, I can do more than just FizzBuzz).
But there is no data, and nobody will ever talk about salary with me, so I just have to make it up. (Digression: why will people talk about their darkest sexual fetishes, but not how much money they make. Do The Corporations really have us by the balls that much?)
My current line of thinking: I read something on HN a few weeks ago that claims top CS students start at $80,000 these days. Having worked with people straight out of college, even the best colleges, I don't think I would have any trouble doing twice as much work over the course of a year. Probably more like 10x, when you include things not dying in production, not having to rewrite the whole app every time someone wants to make a change, etc. So with that in mind, I don't think $160,000 would be unreasonable to ask for if you have a bit of experience and proven ability. You must be worth more than two people straight out of college.
So, I'm going to aim for that at my next opportunity.