Condition: The condition of a coin is one of the most important factors in determining its value. Factors such as wear, scratches, and overall appearance can significantly impact the value of a coin. An 1809 half dollar in mint state (MS) condition will generally be worth more than a coin that is heavily circulated or damaged.
Rarity: The rarity of a coin can also greatly influence its value. The mintage of the 1809 half dollar was relatively low, with only 520,000 coins produced. This makes it a scarcer coin compared to some other half dollars of the same era.
Variety: There are two known varieties of the 1809 half dollar: the "Large 9" and the "Small 9" variety. The Large 9 variety is considered to be rarer and, therefore, more valuable than the Small 9 variety.
Taking all of these factors into account, the value of an 1809 US half dollar can range from around $100 to several thousand dollars. It is important to consult with a professional numismatist or coin dealer to obtain an accurate appraisal of the value of a specific 1809 half dollar.