Goodridge PTFE coated stainless cables are about £6 per pair, rather than £12 each like the Shimano ones.
In use, they work just the same… That is to say noticably better than cheapo cables. Pre lubed outers make a bit of a difference too IMO.
For the doubters out there, running good gear cables makes MUCH more of a difference to the shifting performance of the bike than the quality of the rear mech does. When you work in a shop, and fondle expensive customers bikes with cheap nasty gear cables that they bring in for a service, and wonder why their gears feel horrible, you learn the difference between cheap cables and decent ones pretty quickly!