In my particular case I get paid around $90/hr ($135/hr for overtime, plus paid major holidays). Which comes to around $180K/yr. The full time position I was offered is $130K/yr. There's no way in the world vacation + health insurance is worth $50K.

So if I take a month off, I lose $14.4K ($90 * 160 hours). A decent insurance PPO plan is $1100/month for me any my wife. So that's another $13.2K. So the total is $27.6K. And I don't think that many FTEs have a month of paid vacation.