696 pennies sold for over $16.7 million because they weren't just ordinary pennies; they were the final "Omega" pennies ever minted by the U.S. Mint, sold in rare sets containing 24k gold versions, marking the end of 232 years of penny production, creating immense collector demand and artificial scarcity. Each set included a special Omega-marked coin from Philadelphia, Denver, and a gold counterpart, with the very last set fetching $800,000 alone, making these historic, unique items incredibly valuable.