Toyota Repair: PO420, failure code, toyota parts

Question
QUESTION: I've been quoted $569 for repair to remove this code.  What do you think?  Is this right?  Or should I get another opinion?

ANSWER: Hello, what is the year and model and what engine,how many miles, 4cylinder or V-6? What are they recommending to replace for $569?   

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QUESTION: My Toyota is a 4 cylinder Camry with 165,000 miles. I believe 2.? engine.  Thing is the check engine light does not always stay on.  It does then it doesn't.  I believe the garage wants to replace the sensor to the first cadylidic converter but tells me there is no hurry and it will not effect my car to drive until I decide to get it done.  Also it's best I use the Toyota parts as they hold out the longest.

Answer
This is not usually an O2 sensor code it's a catalityc converter failure code, I think you will end up having to replace the converter, if all they are going to replace is the sensor then that figure seems a little high, the sensor should be about $170 from the dealer and about $100 labor to replace it and retest the system.