I never thought that far
I always thought horns are just money coins like in our world, but the shape is like horns instead of round.
The idea of carrying fangs of certain beasts and calling them coins do come to mind.
Another idea, one I may incorporate into my "GoldEdge" idea, is silver coins called "horns" because the tails side depict either a goat (maybe
Capricorn) or a
cornucopia. Thus the money is called horns because of it. The head side could depict the face of a king or queen.
Either that or the money looks like
Bugles snacks.