Buy the 1944 Steel Penny on eBay The 1944 Steel Penny is one of the most expensive coins in existence. Most probably created by accident, this off-metal error coin relates to WWII, as the copper that was traditionally used was required for a number of military-related purposes as the US battled Axis powers in multiple theatres. Top-Rated Investment: 1936 Buffalo Nickel There are fewer than 30 overall, so you’ll need to be careful if you’re…