What's the cost to replace the Idlers, Pulleys, Belt Tensioner & Serp Belt? on 2007 Dodge Caliber

2007 Dodge Caliber with 107,000 miles, in central Arizona. Bought used, but to my knowledge, belt has never been replaced. Would like to know if the shop is being reasonable on the cost of repair. Also, could this have caused additional damage to the engine?

Asked by for the 2007 Dodge Caliber