The answer to 'how much does shut-off valve cost in Illinois' is that the cost of a shut-off valve can vary widely depending on several factors. Generally, you can expect to pay anywhere from $20 to $200 or more for a basic shut-off valve, depending on the size, material, and location of the valve.
The cost is influenced by the type of valve (ball valve, gate valve, etc.), the size (1/2 inch to 2 inches or more), the material (brass, stainless steel, etc.), and whether it needs to be installed in a difficult-to-access location. Labor costs for installation can also add $50 to $150 or more, depending on the complexity of the job. It's best to get quotes from local plumbers to determine the exact cost for your specific needs.