What is the value of a 1902 walking liberty half dollar?

The walking liberty design was used on half dollars from 1916 to 1947 and wasn't used again until 1986, on 1-oz bullion coins.

If your coin is dated 1902 it shows Miss Liberty's head, not the full portrait of her walking, and the coin is called a Barber half after its designer, Charles Barber. Please see the Related Question for more information