Say what you will about the quality of recent Star Wars games, you'll be hard pressed finding a bad word to say about these. They're official Nintendo DS styli, only with a bonus Star Wars license thrown in, meaning, yes, these are proper DS lightsabers. What's better is that they come in two variants: you can get a three-pack of regular, plastic ones ($8), or you can get a two-pack where the sabers/styli actually light up ($17).
Lightsaber styli [View From Heaven, via Go Nintendo]