Also since you are interested in a piebald cross you may have the advantage of using the piebald het marker to increase your odds. If you get a male het piebald with a strong marker I would bet that his daughters that also show a strong marker have a much higher than 50% chance of being hets. If you produce more than you want to raise keep the markered ones and sell the others as normals. Then you mainly need to worry about if they hit their 50% chance of being het albino.