catalitic converter

can I have a universal catalytic converter put on my chevy aveo 2006.A couple of repair shops said no, but I am thinking that is because you are looking at $150 for the part instead of $400.I have also been told it would be about $100 to fit ? I don't want to get ripped off.
Need it to clear check engine light. Needs an inspection. The dealership told me this was the cause when they put it on the diagnostic computer. Be glad of any hints to get it through inspection. Light has been on for 2 years.Thanks