Several years back the Hunt brothers were charged trying to fix it I think. They had it up to $8/oz if I remember correctly. They would have made an absolute fortune if it worked. Not sure what the penalty was.
It was back around 1981. They drove the price of silver up to around $50.00\ounce. I had a coin collection that was pushing $25,000 and I was only 16 (Whoops, I'm dated...).