The furor over the "copper" cent resulted from a story carried by Associated Press, hyping a local story of a "lost" coin claimed (without any substantiation) to be worth $40,000 to $50,000. The AP writer added another zero to make his headline sound better and the "lost" coin suddenly was the talk of the country.
The facts are that in 1943 the government began striking cents from zinc-coated steel because copper was needed for the war effort. However, something less than two dozen 1943 copper cents were struck on planchets left over from 1942 productions. This is a total for the three mints. Of that number, only one is known from the Denver Mint - showing a small D under the date. This coin sold for $82,500 at auction in 1996, the highest known price for a 1943 copper cent.
Unfortunately many thousands of the normal zinc-plated steel 1943 cents were copper plated, some as a prank, but most as a commercial venture. These, and the normal steel cents can readily be detected with a magnet, such as the one on your can opener. Harder to detect are the additional thousands of counterfeit and altered date coins. Many of the 1948 cents have the 8 changed into a 3, but most of these can be spotted by the stub tail on the lower loop of the 3.