Cost: $4.1M
The Silver Dollar Class 1, 1804 ranks seventh on our list of the most costly coins. The “King of U.S Coins” is the world's most famous 1804 silver dollar, selling for $4.1 million in August 1999. Professional Coin Grading Service classified it proof-68, and in 1999, it was the world's most costly coin, surpassing the previous top by more than double.