2001 Nissan Sentra

My daugthers 2001 sentra (1.8 liter) had a problem code run by a local parts store identified as P1126 that the "throttle control motor relay is open" which we figured was just a relay. The nissan parts department at the local dealer says the that there is no separate relay and I have to replace the whole throttle body for $300. It also ran a code PO430 that the catalyst efficency is low for bank 2. I figured that might be solved when the relay problem is fixed. My daughter is a broke college student and I am a broke father paying for the broke college student. Thanks for your help