I recently purchased a 1997 Lexus ls400 coach edition with 176k miles. As we were driving it home, the check engine light came on. We took it in to a shop that we've been going to for years and got a reading. They said it was the catylitic converters and that they needed to be replaced in order to pass inspection in Virginia. Since that shop only used brand new parts, each converter would cost around 2 grand. I started looking for cheaper alternatives and found some on rock auto and carparts.com for around $42-300 and was wondering if those would be a good idea to buy. Most of the ones I found had warranties so that would lessen the risk.