Holden Astra 2002: High servicing costs

I BOUGHT a 2002 Astra City new, and while it has been a good car, the cost of servicing it would stop me buying another one. My first surprise came at 60,000km when the timing belt and tensioner had to replaced at a cost in excess of $700. I have now reached 120,000km and the belt has to be replaced again, and Holden recommend I replace the water pump as well at a total cost of $1100. Had I been made aware of this in the first place I would not have bought the Astra. Holden says it is detailed in the service book, but I argue that not many people sit down and read the service book. I was interested in buying a Holden Viva, but I note its belt is to be replaced every 60,000km as well. Can you give me some idea of the replacement distance of timing gear belts on comparable Toyotas?