Based on the 2014 price guide from CoinStudy, the 1957 Franklin half dollar is less rare than most Franklin half dollars. A 1957 Franklin half dollar in mint condition with no scuff marks or nicks is considerably rarer than coins with some markings and discoloring.
The U.S. Mint produced 5.114 million 1957 Franklin half dollars at the Philadelphia mint facility. It also produced 1.24 million proof coins, which are more rare than the coins produced for circulation. The Denver facility minted 19.966 million 1957 Franklin half dollars. These coins can be worth around $38 in mint condition, as of 2014. The minimum value of the coin is based on the price of silver, of which the coin contains 0.36 ounces.