Can we use a contractor or supplier that is not a Goal Construction preferred one?

We have screened and worked alongside our contractors and suppliers for years and can vouch they are the best in the business with regards to the efficiency and quality of their workmanship, so we would not prefer to allow quality to be sacrificed by using someone else. It is because we have worked alongside with these same individuals for years that we have built our own reputation for high quality so we can assure you that you will only get the best service.