2003 Toyota Corolla Catalytic Converter

I just went to get my car inspected, and was told that in order for it to pass inspection, it would need a catalytic converter. When I got the bill, I was charged $1121.50 for the catalytic converter (just the part itself). The total bill was $3000. When I got home, I googled catalytic converters online, and see that they sell for between $300 and $600. Is there any reason why it would cost $1100? The O2 sensor was $142, and the springs, bolts and gaskets were also priced separately. This did not include labor.