Originally Posted by kschachn
Yes, they have a variety of platinum group metals that have some value.
And it isn't illegal to sell a used one, but it is required that you have the means and ability to test the converter for structural integrity and performance prior to sale. Very few scrap yards have this ability so the practical conclusion is that no one is selling them.
Did all of those eBay auctions actually complete or were some terminated early?
Don't know about your state. But in California it IS ILLEGAL to sale used catalytic converters to consumers. Only to the scrappers.