I know this adds to the cost, but if you decide to change the timing belt and its tensioner, it is worth also changing the water pump since this is driven by the timing belt and probably will not last forever. I would also consider replacing the thermostat, another item that will not last forever and requires draining of the anti freeze. This then helps the case for replacing the anti freeze. If this helps, our C3 1.4 sx, 03 reg is now on 35k miles. It has had the dealer 2 year services and timing belt has not been mentioned. However, last year I removed the top cover over the belt (only 2 bolts ?) and the belt looked in good condition and also no signs of any oil contamination. iannez - do your costs include the parts (belt, tensioner, anti freeze) - they seem reasonable and you will be giving a warranty of your work on the belt change which a DIY change will not provide.