The spread on physical currency is always ugly. That includes gold and silver coins minted by the treasury. You also have to realize that the price is not the actual cost of the gold it was derived from but also the overhead that goes into creating the coin.
A design for the face and back have to be created and then engravers are tasked with creating the molds, all handcrafted. With the low volume of resale for these coins, relative to pennies, nickels dimes and quarters the manufacturing costs tend to raise the price per coin much higher.
Frankly coins are a waste of money. It is better to buy bars. Less overhead in manufacturing and you have a choice in the various mints across the world that sell gold bars.