How much is the 1977 Lincoln-Kennedy penny worth?

Not much, such a coin was not produced by the US mint and was done outside of the mint which pretty much ruins all collector value. Serious collectors will view it as a damaged coin (and 1977 pennies aren't worth much anyways) and it is worth a cent to collectors and perhaps a bit more to someone who collects Kennedy or Lincoln memorabilia but no serious coin collector would buy it for any more than a penny.