The answer to the cost of backflow preventer repair in your area is that it can vary significantly depending on several factors. Typically, the cost for a professional plumber to repair a backflow preventer can range from $150 to $500 or more, depending on the complexity of the repair and your local market rates.
The main factors that influence the cost include the type of backflow preventer, the extent of the repair needed, the labor rates in your local area, and whether any parts need to be replaced. Additionally, the accessibility of the backflow preventer and the time required to complete the repair can also impact the final cost. To get an accurate estimate, it's best to get quotes from licensed plumbers in your local area.