So did yours rust, wear or break? Or, did you buy it with an after market and don't like it?
I bought a Yamaha Virage 1100 a few years ago and it had loud, aftermarket exhaust on it. When I got off the freeway it would backfire loudly. I went to the junkyard and bought the original pipe and the bike ran fine for years.
I would try a motorcycle junkyard, a quick look on Babbits shows the pipe is over $800 new and the muffler part is over $400.