This week... I found a local supplier of stainless steel, and bought a 3m length of 8mm stainless rod (Good value round these parts at €6). They only sell in full lengths. I cut new X and Y axis rods. The stainless was easier than I thought to cut even by hand with a hacksaw. Mark the desired length carefully and grip the rod in a vice, protecting the rod from the vice jaws.
Once cut it's a good idea to round off any sharp edges with a flat file.