Some pipes can be repaired. On any joint where there is a piece of black pvc sewer pipe inserted/glued into a 90, union or other coupler, you can cut the pipe clean at the joint and then hone out the joint and reinsert a new pipe. Your local plumbing shop will sell the tool for honing out the old pipe.
Here is a link to the tools. If the joint isn't something you can get to, obviously this won't work.
Cutting Tools