Parts:
Water pump (new): $40 - $100
Additional gaskets, seals, and coolants: $10 - $25
Labor:
The labor time for replacing a water pump on a 1999 Buick Century is typically around 2 to 3 hours. Assuming an average labor rate of $80-$100 per hour, the labor cost can range from $160 - $300.
Please note that these figures are only estimates and the actual costs may vary depending on the vehicle's condition, geographical location, and the specific auto repair shop. It's recommended to obtain quotes from different mechanics for a more accurate estimate.