U.S. Silver Dollars Below Spot Price
Morgan Silver dollars were minted between 1878 and 1921. Peace dollars were minted between 1921 and 1935. Both coins are still available in abundance and your odds of getting these below spot price are good since there are many common date coins for these U.S. type sets.
You will notice that I filter out certain keywords as well as exclude all listings under $5 in value. A Morgan or Peace selling that low is virtually non-existent but miniatures and other replicas are abundant in the <$5 price range.
Morgan Dollars Under $15
Between 1971 and 1976 there were Eisenhower dollars made of 40% silver.