It will depend on your vehicle, what needs replacing and where you live. Typically you are looking at $150-$800 dollars.
How much should a tune up cost?
It's not just a tune-up anymore. This site gives a pretty good view of what maintenance should be for a newer vehicle and costs of such.
Well, it all depends on the model of the car and the quality of the parts you are purchasing. I would always recommend buying quality parts like the ones offered by Crow Cams.