What is the value of a Kennedy half dollar with a D mint mark?

For most coins you really need to post a coin's date as well as its mint mark to get an accurate evaluation. Fortunately Kennedy halves are easy to value because so many of them were struck and there are no rare dates.

1964 : about $7 for its silver content

1965-69 : reduced silver content, about $3.25

1971-present : made of copper-nickel, worth 50¢ only.