Ron Guth:
Most dates in the Capped Bust Half Dime series are of equal rarity. The only exceptions are 1836 and 1837, which have lower certified populations than the other dates. Thus, the 1830 is just as good a choice for a type coin as any other date in this series.
Among the certified Mint State survivors, the most common grade is MS-63, followed by MS-62 and MS-64. In grades above MS-66, the 1830 Half Dime is very rare, and the finest example certified by PCGS (as of January 2012) is a single, amazing PCGS MS-68.