Call Banks. Or you can go PVC pipe. You have to paint them but it's economical. I replaced some on a TDB a few years back with PVC pipe and clips. The paint doesn't hold on the best but Krylon fusion is cheap. You just touch up as needed.
Didn't crack because you don't drill into the pipe. You just cut to length with a hacksaw and paint and then put on the painted end caps. What I liked about it the most was that the pipe snaps into the clips so if a dog would get a foot in the rail is could pop out of the clip. Check out the photos: