You can use the Repair Pal Estimator to get an idea of that cost. The price will vary from one shop to the next. The thing to ask when you do have that work done is whether they install the same spark plug that the original manufacturer uses. Some shops buy the cheapest parts available, and that may not be the best for your car. An Oldsmobile Alero probably uses AC spark plugs from the factory.
somewhat helpful, still doesn't help me understand what I should be paying. what about cost of coils, do they need to be replaced as well, if so, how much. And, if they're mfgr spark plugs how much are we talking about for parts, not including labor?