What should I pay for a full tune up inc.spark plugs, air filter, wires, gasket?

First, thank you for your reply. I would have the car checked to see if it is due for a coolant flush or timing belt change. On the norm, what should I expect to pay for a tune up with and without these add-ons? I have been given a rate of approximately $200-$210 from my mechanic and the dealership for plugs, tune up and wires and gasket. The dealership said it would check the wires and if it doesn't have to be changed, the rate for the plugs would be $156 (before taxes). Would I be correct to assume that if the price is basically the same, I should go to the dealer? Also, I just had an oil change with a new filter so I am guessing that both my dealership and mechanic would reduce their price if I already have a new filter. I await your reply and again, thank you.