Male V/S Female Brain

A family went to a hospital, where one of their relatives would be having a brain transplant. One of the relatives asked, "What will the cost of a new brain be?" The doctor replied, "A female brain costs $25,000 and a male brain costs $50,000." The men smirked, but one of the females asked, "Why is that, doctor?" "Well," the doctor replied,” the female brain is less because it has been used."