The number one factor that determines price is Supply and Demand of the coins themselves.
One coin may have the exact same mintage as another and may be the same condition, but if only one is sought after, that will determine the price.
The Condition of the coin itself.
Some coins are seemingly only found in low conditions and jump exponentially in higher grades, while others seem to always be in high grades and don’t seem to move much in price
The date and Mint Mark of the coin.
Sometimes, coins that are minted only one year apart can be starkly different in price, and even some minted in the same year can vary dramatically in rarity and price depending on where they were minted.