An attempt to document the cost of mining silver (and not an endorsement or rejection of this view) --
http://seekingalpha.com/article/1496552-first-quarter-2013-true-all-in-cost-silver-industry-figures-unsustainable-silver-pricesThe 'money' quote --
According to the recent quarterly numbers, it shows that many silver miners produce silver around $25 per ounce on a true all-in cost basis.
FWIW --