Driving some of the wild commodity prices is the short-term prospect of a spike in inflation. The quantitative easing (QE) policy runs the very serious risk of overshooting the desired stimulative effect, which leads to rapid decline in the value of the USD and hence a big spike in the commodities traditionally valued in USD... oil etc. Now... since QE2 we've not seen much sign of inflation at all and oil is rising but in a gradual and predicted way. Yet certain commodities are being priced even further beyond reason. So this begs the question, who really believes these commodity prices will hold?
Buy land not precious metals, that would be my investment advice! At least you can put up a tent on it