Assuming you are referring to a lug nut stud on a car, the cost to replace it will vary depending on the make and model of your car as well as where you take it to get repaired. For example, at a dealership, they may charge more than an independent repair shop. The part itself may also cost more or less depending on the make and model of your car. If you need to have the entire wheel assembly replaced, that will obviously cost more than just replacing a single lug nut stud.