Despite being a borderline fantasy story, I dislike ignoring the idea of commerce. For example, in movies I often see the characters jump out of taxi cabs without paying. But my story does have a 'created world.' It wouldn't make sense to use dollars or pounds or yen. Out of desperation I have used the term 'ducat' as a working term until something better comes along. How have you guys dealt with this problem? I have considered some item that just could be 'swiped' but that seems too much like science fiction or plugging in a Prius.