I'm going to chime in on the difficulty in determination of noise source on the serpentine belt line. I spend many hours and parts chasing this down......mine would ONLY make the noise at a certain RPM.
If you remove the serpentine belt and spin each item by hand....you MIGHT be able to track it down.
I found my tensioner pulley bearings right away this way.
In my case, the difficult one was the idler pulley, but I think MOST cases will be easy to tell with these pulleys.
The pulley units are cheaper than the water pump, alternator or power steering pump.......or A/C compressor.
The bolt holding the idler pulley was a real bugger to break free.....took some serious abuse to get mine loose.
Power steering.....periodic replacement of the power steering fluid (use transmission fluid) is advised.... Any air bubbles visible in the fluid when you look in the reservoir are bad.....air bubbles in the power steering fluid WILL make a nasty racket.