2001 Grand Prix GT Steering Problem

All of a sudden my '01 GPrix became very difficult to turn the steering wheel to the right. I added power steering fluid but it didn't help. Turns fine to the right but not left. Stopped at a mechanic and he said the steering rack needs to be replaced for $450.

Can anyone confirm this diagnosis and/or if that is a fair price?
New to the area and not familiar with this shop and don't want to get screwed.

Thanks!