Computer Chairs

[Shrubwise]

It's time for a new computer chair. I'm spending more time sitting on my ass, in front of the screen. My neck, back are beginning to hurt. I bought a cheap chair from Staples or some shit like 3 years ago and it's just not cutting it.
Like most things in life, I believe you typically get what you pay for. If I am going to be spending long periods of time sitting at my desk, I want to be comfortable. I'm willing to drop some decent $ for a good chair. A Google search for "ergonomic desk chair" yields lots of results, mostly fancy-looking, very expensive chairs ($500+) I would spend the $500 or more, if I knew it was worth it.
What chairs do you guys use? Are you satisfied, does it help support your back, and how much did you spend?