What is the value of the most expensive coin?
For U.S. coins, it varies from time to time depending on the amount of interest in a particular coin and when it comes up for sale. Prices have leapfrogged over each other during the last several decades. The 3 most prominent rarities right now are the 1913 Liberty Head nickel, the 1804 silver dollar, and the 1933 double eagle. Some recent sale prices: One of the 5 authenticated 1913 Liberty nickels - $3 million. Type I 1804 dollar - $4.14 million 1933 double eagle - $7.6 million. This date's legitimacy has been a subject of much controversy since technically no 1933 double eagles were ever supposed to have been released from the Mint. However at least 10 have surfaced in recent years.
Depends on what the coin is made out of. The coin has absolutely no collector value because it wasn't made by the US Mint. Any value comes from the material the coin was made out of. If the coin was gold plated, it would be worth a couple cents at most. If the coin was solid gold, it would be worth the value of the gold, but no more.