Value of a 1974 Turks and Caicos Islands Winston Churchill Centenary coin?

I bought it in 1974 for $20.00 US and have no clue as to its value now. World Coins, 2003 edition, lists it at $17.50 Uncirculated and $25 Proof, and these pseudo-coins minted only as collectors' editions seldom appreciate much. However, this coin contains about 1.15 troy ounces of silver, making it worth at least $20 as bullion. If collectors value it lower than the precious metal content, many may soon get melted.