private NzEstimator()
 {
     //todo nz uses the same formula for now
     LabourEstimator = new LabourCostEstimator();
     PriceEstimator = new PriceEstimator();
 }
 private AusEstimator()
 {
     LabourEstimator = new LabourCostEstimator();
     PriceEstimator = new PriceEstimator();
 }