According to CoinStudy.com, the value of a half dime can vary greatly depending on the date the coin was produced, the overall condition of the coin and the mint mark that indicates where the coin was produced.
The oldest half dimes, called the Flowing Hair variety, were produced between 1794 and 1795. These coins can be worth between $750 and $7,850. The newest half dimes, dubbed the Seated Liberty Legend on Obverse type, were produced between 1860 and 1873. These newer half dimes are only worth between $11 and $110. Old coins are graded according to their condition. The better the condition of an old coin, the more valuable it is.