Cost to replace a Harmonic Balancer and serpentine belt in a 2001 Lexus GS300.

My car was making a loud screeching noise when I tried to turn my steering wheel.  It did this a number of times.  I was told that I needed to replace the Harmonic Balancer and belt.  Not sure if they were talking about a serpentine belt or some other belt.  Total repairs including labor cost $954.00.  I called Lexus to get an estimate because I thought that was pretty pricey coming from a non-dealer repair shop.  Lexus charges about the same.  I contacted another mechanic and he said $600 to replace the Harmonic Balancer; however, he said nothing about the belt.  I've checked several sights that talk about replacement/repair and most seem to say this shouldn't cost that much to replace.  Just tired of getting ripped off by these mechanics.  If your labor charge is high, just say that, but don't over charge me for a part that you got  for less than $100 and try to charge me triple the price of that.