The price to replace a drive belt

I think that you may be confused with the timing belt. The drive belt is the belt that runs along the front of the engine that powers the accessories like the power steering pump, A/C compressor, alternator, etc. That is very inexpensive and quick to replace. The timing belt on the other hand, keeps the crankshaft and camshaft(s) in time with each other, and a broken belt will cause the engine to stop running and can often cause engine damage with valve to piston contact. I would recommend getting the timing belt changed soon, along with any idler pulleys/tensioner, as well as the water pump, thermostat, and drive belt(s). I would count on roughly $500 for everything.