I took my car into the dealership for maintenance, and they said they recommended replacing the timing belt at 7 years even though the car only has 55K miles on it. It is a 2004 so it is just 7 years old. He said it would cost $900 which I don't have right now. Is this something I should do at the first opportunity? I always thought it was at 100K miles so it wasn't on my radar.