Hard to say. $40,000 is less than what auto factory workers make. Yeah yeah, I know everyone say they're overpaid...but I thought that 25% less than their number was a good guess. But I can't say for sure, of course.
At any rate, I would point out that even at $10 per hour they'd be making 10x what Foxconn employees do. So even your lowest guess would raise the cost of the phone significantly.