Spark plugs and serpentine belt

[Henstepper]

Was wondering what the average cost is to replace spark plugs and the serpentine belt on my 09 Aurion? From what i understand to get to the back plugs the window wipers and cowel has to come off correct? And with the belt it's kinda hard to get to. Wonder if they use the remove tyre method. both would bump up the labor costs?

[campbeam]

I do not know about the labour costs.  

I would expect a time estimate of less than 4 hours to replace the spark plugs. Replacing the front 3 spark plugs [plus coil packs] took me approx. 15 minutes. Other time is taken up removing/refitting the windscreen wiper assembly and the cowel to have access to the 3 rear spark plugs. 

I would expect a time estimate of 30 minutes for replacing the serpentine belt which is straight forward. Most time will be taken with correctly fitting the replacement belt around the various pulleys.