There is a website called coinapps and you can type in how many of each silver (or gold) coins you have and it multiplies the content by the current value of silver and tells you the exact melt value at any given time. Has each coin by date, and calculates the 90%, 40% Kennedy's and 35%
War Nickels.
I would say at any time if you can buy coins for melt then its a good deal. You are buying for melt value which is hard to find, and on top of that, if they missed a key date, or a coin in good condition and you can sell it over melt then you made money.