It all depends on when or how the timing chain snapped. Did the timing chain snapped while the cavalier was in motion or when the motor is running? or is it just a timing chain tensioner that gave up or became loose and creating so much noise? I really hoping that it is not the first I mentioned, because you will be spending a lot of money into it. However, if it is the second scenario that I mentioned, the part will cost you between 127 to 215 dollars. Multiply that by 1.5 your repair cost will be approximately 191.50 to 322.50 + spark plugs, motor oil, oil filter, engine coolant and other stuffs your mechanic will add.