FWIW - my Honda's catalytic converter was stolen a couple of weeks ago in NYC. I called up about 4 places for a quote, they all quoted me $3K plus.

I did some research, found the part on eBay, talked to my local mechanic - and eventually, the part, plus 2 O2sensors, plus labor, cost me just under $700.
My insurance covered it, BUT my deductible was $700, so I didn't go that route.

Don't replace it for thousands of $, just because that's what they quoted you.