Usually I desperately ride to the hardware store for generic branded pre-cut ready to fit kits called "brake wire set", "shifting wire set", mostly because I am dying to finish a build. It frays on first fitting and the housing is so stiff that I have taken to bringing it into the bedroom to convince people I've still got it, and then I order the more expensive branded stuff from the internet, paying a large premium while having to wait makes it feel like a treat.