Have you shown the NPC results to your parents?
If you parents are fine with the cost, I would be inclined to believe them.
Regardless of the answer to this question, you also need to make sure that you have two safeties lined up that you would be happy attending.
If you are very happy with your safeties, then two safeties plus Duke might be all that you need to apply to. However, if this is the plan then first make sure that your safeties really are safeties. Then ask yourself the question: “If I am turned down at Duke and get to attend one of my safeties, is there another school that I would regret not applying to?”.