A 1943 copper wheat penny can be worth an extraordinary amount because it was never supposed to exist in ordinary circulation. During the Second World War, the United States Mint planned to produce 1943 cents from zinc-coated steel so copper could be reserved for wartime needs. A small number of copper blanks from the previous year apparently remained in the presses and were struck by mistake.
Collectors prize those accidental copper cents, and examples authenticated in excellent condition have been valued in the tens of thousands of dollars. Figures around $85,000 are often mentioned for a strong mint-state example, while the exact price depends on condition, origin, demand, and the result of professional grading.
The rarity has also created many counterfeits. Some altered coins begin as 1948 copper cents, with part of the final digit filed away to resemble a 3. Others are ordinary 1943 steel cents coated with copper. A simple magnet is therefore a useful first check. A genuine copper cent should not stick, while a copper-plated steel cent normally will.