I had to do this job on my brothers gt a while ago. It had 120k on it and it was bringing on the engine light because the cam was retarded. The chain was stretched so it needed a chain, guides, tensioner, gaskets, water pump, coolant and belts. Find out what the quote included because of it includes the water pump it's probably a good price. The pump includes the supercharger clutch and is genuine only.
You can always ring a few other places and see what they quote. It's not great that a timing chain can't even last as long as a belt.