The cost to replace the valves in a 2000 Volvo V70 XC can vary significantly depending on the labor rates and parts prices in your area. On average, you might expect to pay between $1,000 to $2,500 for parts and labor combined. It's advisable to get quotes from several local mechanics or dealerships to get a more accurate estimate. Additionally, other factors such as the condition of the engine and any additional repairs needed can influence the overall cost.