Q. What is the average cost of mining per ounce?

A. The average cost of replacing and producing an ounce of gold rose to $428/oz in 2005, a ten-year high, according to Metals Economics Group, based on a study of 18 major gold producing companies. However, costs vary widely between companies and the mines themselves. – World Gold Council

I read elsewhere that the current production cost is $600-700/oz on average.