The price of propane actually became negative, hitting an unbelievable -0.625 cents per gallon.

It's hard to believe that the price of a productive commodity could become so beat down by the market that producers would practically have to pay you to take it off their hands.

Now that's cheap. And completely nuts.

This actually happens from time to time with certain commodities. And there are a number of reasons for it.

A negative price might imply a dramatic oversupply where the cost of storing the commodity exceeds the benefit from owning it.

Sometimes even something like real estate can have a negative value—perhaps when a building is in such decrepit condition that the cost of tearing down the structure exceeds the land value.