Modern Coin Mart via eBay offers 10 troy oz. .999 Silver Bar from the S.S. Gairsoppa Shipwreck for $239.99
with free shipping
. That's $85 off and the lowest total price we could find. It's one of almost 7 million silver ingots that sank when the S.S. Gairsoppa was torpedoed by a German U-Boat in the Atlantic Ocean on February 17, 1941. It's certified to be 99.9% pure and sealed in protective soft plastic.
Note that silver is currently trading at around $19.38 per troy ounce. Also note that it won't arrive for Christmas; the earliest delivery time is December 27th.