About ten cents to a quarter at most, I reckon. I sold these (even the readably dated ones) in my 3/$1 bin at my antique mall coin booth ten years ago. In labeled 2x2 holders. You won't get rich off that, but it's still a handsome enough coin (aside from Franco's face).
The ones that are worth a little more than hardly anything are the 1947 pieces with "19" and "56" in the stars. And of course the ones issued for the 1951 numismatic exhibition which have an "E" and a "51", but those were not issued for circulation. Christian