The variation on the prices of ingredients has to be almost negligible for those drinks. Even in a huge cup you have at most $0.40 worth of milk and $0.30 of c

The variation on the prices of ingredients has to be almost negligible for those drinks. Even in a huge cup you have at most $0.40 worth of milk and $0.30 of coffee beans (and that's generous, you could get specialty beans at that price).