I have to say, this one is going to be hard to beat:
"Used to be gold, but now lead is the most expensive metal," said Donald Richards, 37, "And worth every penny."
In response to the year long ammunition shortage due to Gun Control fears of an Obama Administration. (Thankfully we have successfully stalled him on Health Care that he hasn't gotten around to gun legislation yet)
As of this posting, Gold was listed at $995/oz. or $14,510 per pound. Lead is priced at 96 cents per pound.
Lead, not truly "the most expensive metal", but we know what you mean... wink wink!