Depends on when your contract started, from 12.50 a month per month of contract left, to 20.00 a month per month of contract left currently. I think the 20.00/month rate started in September 2007, IIRC, but that may not be right. I am sure someone knows the dates better than me.
They make it hurt if you change your mind. Or lose your job. Or gas goes up. Or you lose your house. You WILL pay that fee if you cancel. I think maybe if you die you might get out of paying it, but I wouldn't be so sure.