http://www.kitco.com/ind/Saville/20120612.html

Here is a quote from the above link specific to copper:

1. As is the case with oil, in IA terms the copper price probably made a secular peak in 2008. As is also the case with oil, the IA copper price is now only slightly above its 40-year average.

Falling demand due to a global recession over the next 12 months could cause the copper price to drop back to $2.00, but we doubt that it would stay that low for long because economic weakness always prompts central banks to boost the money supply. However, future rounds of QE (or whatever other name they give to the money pumping) probably won't do anywhere near as much for the IA copper price as the earlier rounds did. Another way of saying this is that copper probably won't be one of the main beneficiaries of future monetary inflation. One reason is that China's construction boom is turning to bust. Another is that the high prices of the past six years have increased the current and future supplies of this metal.

In 2012 dollar terms we think a copper price in the $2.50-$3.50 range is about right. We would therefore steer clear of copper mining projects that required a copper price of much above $3.00/pound to be economically robust and we would be wary of low-grade copper projects with unknown economics.