The best time to negotiate your salary for a new job is the moment AFTER they say they want you, and not before. Then it becomes a game of chicken for each side to name an amount first, but it is to your advantage to get them to give a number before you do.
"We are all alone, born alone, die alone, and—in spite of True Romance magazines—we shall all someday look back on our lives and see that, in spite of our company, we were alone the whole way."