$275 to change the plugs, right around $200 for the transmission service (which is really the only thing I wanted to have done; everything else I can do myself and certainly will do in the future) and $50 for the oil change. And just for those three items I sat in the dealers waiting room for a little over four hours. That's with an appointment.
And that isn't everything Ford recommends at 100K, oh no, there is also the rear differential, the coolant system flush and fill and the fuel system servicing which would run another $400 or so. And that doesn't include having them look at the little issues I'm having with the car, such as the blend door actuator needing calibration or the oil life monitor staying at 100%.
When they asked me why I hadn't brought the car in to them for a while I just laughed and said "Gee, I don't know." Fortunately I have a full set of tools, basic mechanical knowledge, and a
whole slew of friends who love Mustangs and know how to do everything
associated with them, so it's not likely they will see it again for another long time.