I think there is some confusion in the article(s) quoted in this thread.
On March 4, 2013, Smartplanet.com had an article titled "Feeling the pinch of China's labor shortage", by Channtal Fleischfresser, where the author stated in the fourth paragraph that Foxconn's margin on each Apple iPhone produced was $8.00!
This maybe the confusion generated in the other articles as margin is the profit made on each of the tens of millions of units Foxconn produces for Apple and not their actual manufacturing costs which presumably would be higher.
Here is the link to the Smartplanet article:
John Stahl Aljon Enterprises
***** Moderator's Note *****The Smartplanet page cites a slate.com story from September, 2012, which is entitled
"Foxconn Getting By On $8 Per iPhone"
... which may be the source of the eight-dollar figure that has been under debate.
The Slate story is at
Bill Horne Moderator