There is no universal answer to this question since the cost of a new thermostat will vary depending on the specific model you choose and where you purchase it from. However, you can expect to pay anywhere from $20 to $200 for a new thermostat. If you need help installing it, you may also have to pay a professional fee which could increase the overall cost. When deciding if replacing your old thermostat with a new one is worth the investment, be sure to consider how much money you will save on your energy bill each month. Many newer models are designed to be more energy-efficient, which means they can help you save money in the long run.