Use new sensors. O2 sensors are like spark plugs. They get old and clogged. 60-15= $45 is not worth breaking the law, praying that a prius will be at my local junkyard, junkyard owner/worker will risk his business license/Job for $15 & possible return trip few months later to buy another one. I would highly suggest to replace with a denso or bosch sensor and forget about it for another 100k miles. Mine lasted for almost 180k.
Converters online are refurbs/rebuilds. But i agree that its better to have a shop like art deal with these issues. However this is not a option for people living outside of bay area. If you live in reno or fresno you have to use a local shop or sell your first born to a steallership. I say keep your first born and find a honest mechanic
We just bought a 2002 Prius and we went to the local Toyota dealer to find out why the check engine light was on & they said that we need a new catalytic converter. One can find ones but ... none of the ones I've found meet California standards. We're taking the car into Luscious Garage this morning and will find out whether or not it needs to be replaced or not. Car still acts sluggish when accelerating on the freeway with noise when accelerating. Dealer claims he drove it for 5-7000 miles with no noise or problems. We think he's lying.
What shop did you use ? We live in Concord/Martinez and are trying to find a good local Prius repair shop.