The answer to 'average cost of supply line' is that the typical cost for a basic supply line can range from $10 to $50, depending on several factors. The price can vary widely based on the length, material, and complexity of the installation. Homeowners should expect to pay more for longer runs, specialty fittings, or if the supply line needs to be routed through walls or floors.
The cost can also be influenced by the specific plumbing fixtures being connected, the difficulty of the installation, and whether any additional work like drywall repair is required. It's best to get local quotes from licensed plumbers to get an accurate estimate for your specific project.