How much is a 1986 giant 1 pound silver eagle worth?

This is NOT an official US Silver Eagle. It's a bullion piece from a private mint made to look like a Silver Eagle. Assuming it's .999 fine silver, as of 10-11-11 silver is $31.79 per ounce and a pound has 16 ounces so... $31.79 X 16 = $508.64