1997 Ford Taurus 1997 Ford Taurus SHO Major tune-up

Hello,
Would you be so kind as to give me a general idea of a labor hour and parts estimate for a 1997 Ford Taurus SHO major tune-up?
I have been quoted almost $400.00 for simply replacing 1 faulty ignition coil and 1 autolite double platinum spark plug at our local Christian Brothers Automotive franchise facility.
When he finally is able to access the 4 most difficult plugs and coils, each of them could be possibly be found to be faulty. Doesn't this seem outrageous to you? Is there a guide or resource that I might peruse to give me a general idea as to simply the labor hours needed for a major tune-up, excluding any parts that might be required? Would you kindly give me an idea of what questions to ask and or what to look out for to ensure that I am certain to receive a full and major tune-up? I realize the added expense associated with working on the SHO model. Kindest Regards from Little Rock Arkansas (Mark)