If the pipe is good, the muffler casing looks like a fairly simple gas-weld repair job. If the entire pipe is shot, it might take a couple of hours to make one out of a bunch of standard pipe bends. That would be a bit tricky though, because you need to achieve a fairly precise fit to get it to sit in the correct space without hitting anything. So, it depends how much MTD want for a new part, and whether you know a gas-welding enthusiast.
