pre cat catalytic

My mechanic Told me my pre cat is bad. He said it's a pain to fix. What am i looking at here price whys. Can i buy just the pre cat or do i have to buy an exhaust manifold with the pre cat. Any help would be greatly appreciated...

Like the title says my Protege 5 needs a new Pre Cat, ive read that RockAuto has a good one. Any more suggestions? Need to buy this week....