Your car is due for timing belt replacement based on mileage. Better to do it now than before it breaks.
As for cost, here at my shop, the price to replace just the timing belt--nothing else--would be about $350. To replace the timing belt, hydraulic timing belt tensioner, timing belt pulleys, camshaft and crankshaft oil seals, water pump, thermostat, bypass hose, accessory belts, coolant, about $950.
It's reasonable to expect a water pump, oil seal, tensioner, etc. to last 100,000 miles, so those parts may not show any fault now. But if one of those parts fails 2 years from now, you'll be paying for the same job again, and then some, also with the chance of doing major engine damage.
It's your car and your money, you decide. Any reasonable shop should give you options as to how to maintain your car.