It would most likely be a pricey black market. I doubt the government -- especially one like we have now -- would allow a free an open exchange of precious metals. After all, the government's goal is to steal our wealth via currency devaluation. Can't do that if we're converting all our wealth into metal. Remember FDR's confiscation of gold in the 1930s.
Still, I don't see any other option. The Fed is printing like mad....