Is it just dented or bent, and you're worried about decreased performance? Or is there a hole in it?
Either way, you want to replace it. It is not cheap. You can't simply order a piece of pipe, then bolt it on. The entire exhaust manifold and catalytic converter is a 1 piece unit. But as you can see, it is a bolt on installation. Bolts at the exhaust manifold. Bolts at the midpipe. You will want new gaskets. While you're at it, I would also install new O2 sensors. Which makes it all a little more expensive. But you don't want to finish the job, then have an exhaust leak. The O2 sensors have to be slightly fouled already, so why reinstall them, since you will eventually need to replace them?
If you do decide to replace it, please chronicle the journey and take us along. A few of us would love to see photos, or even a video.