It depends on the year, make, model and engine of your vehicle. Ask any mechanic at any repair shop. They give you a free estimate on parts and labor. They will tell you exactly what the parts cost and exactly what the labor cost. You can get free estimates at as many shops as you want. Assuming your vehicle even has a timing belt, your owners manual tells you when it needs to be replaced. If you don't have an owners manual, ask any guy standing behind the counter at any auto parts store. If you do have the belt replaced, replace all other belts, the water pump, the thermostat and all coolant hoses at the same time. If you need to know why, ask the mechanic and he will explain how that saves money for you.

Depends on engine type and make, Range between $150 - $250.

Didn't spend much time on that question, did you? It's almost as if you thing the price is the same on every make, model, engine every made. You couldn't possibly think that, could you?:

After you rethink your question, you might want to repost with year, make, model, and engine.

Varies from vehicle to vehicle from a possible low of $600 to a couple of large.