The answer to 'shut-off valve installation cost' is that the cost can vary significantly depending on several factors. Generally, the installation of a shut-off valve can range from a few hundred dollars to over a thousand, depending on the complexity of the job and your location.
Some key factors that influence the cost include the type of valve (ball, gate, or globe valve), the accessibility of the plumbing, the need for any additional plumbing work, and the labor rates in your local area. Hiring a professional plumber is usually recommended for this task, as they have the necessary expertise to ensure the job is done properly and safely.