Preheat oven to 450 degrees F. Combine the baking mix, buttermilk, sugar, salt, and half the margarine in medium bowl. Mix until well blended. Turn dough out on to a floured surface and knead for 30 seconds, or until dough becomes elastic. Roll dough to about ¾ inch thick and punch out biscuits using a 3-inch cutter. Arrange the punched out dough on an ungreased baking sheet and bake for 10 to 12 minutes or until biscuits are gold on top and have doubled in height. Remove the biscuits from the oven and immediately brush each with a light coating of the remaining melted margarine. Serve warm.