I've personally gotten prices ranging anywhere from $400 to $900 to do it on my 1997 Pathfinder. It all depends on what they're actually quoting you. The ones on the higher end also include a new water pump, new cam and crankshaft seals, coolant, new belts, thermostat, etc. Basically since they're already right there when they tear it down to do the timing belt it makes sense to do this other stuff since the additional labor is minimal if any.