The 1964 United States Proof Set is a One Year Type Proof Set that is almost 40 years old. 1964 was the only Year that the Proof Kennedy Half Dollar was made in 90 Silver. Since the United States Mint has starting selling Silver Proof Sets in 1999, their value has been steadily increasing, with the most recent sets starting at 37.95. When you consider the 1964 Silver Proof Sets in the light of these facts, THEY ARE A GREAT VALUE! Sure to increase in the future.