The answer to 'how much to replace switch' is that the cost to replace a light switch can vary widely depending on several factors. Typically, the cost for a basic light switch replacement by a professional electrician can range from $50 to $150 or more, including labor and materials.
The specific cost will depend on the type of switch, the complexity of the electrical work required, the accessibility of the switch location, and your local labor rates. Replacing a simple single-pole switch in an easily accessible location will be on the lower end of that range, while replacing a more complex dimmer switch or one that's harder to access may be on the higher end.