My choice for a wildcard future undervalued coin is the common Silver American Eagle. They can be acquired for small premiums over bullion value, but hold potential for future appreciation. At some point it seems probable that the price of silver will rise, perhaps dramatically, probably in relation to a shortage of industrial silver. Many will be melted. The US Mint will discontinue the production of the coin in order not to make the shortage worse. The day that happens, SAEs will become a highly desired collector's coin, not just a bullion coin. It's also very beautiful.
They used to be but right now they are HOT IMHO---I rememebr them selling for about $70 for a nice one....now most are selling for over $150. Speedy