Hobbies And Interests
Real Lightsabers
Real lightsabers have not been invented because the science required to build such an item does not exist. If this should change, they would likely be subject to severe legal restrictions.
Future Horizons
Future Horizons custom-builds plasma sabers. Such an advanced device will set you back a few hundred dollars as of September 2009, but it does glow like a real lightsaber and makes all the right sounds.
Replicas
Master Replica and Force FX make realistic replicas of lightsabers from the movie. They are not cheap, but they do make lightsaber sounds and look like they're extending out from the handle.
Other Lightsabers
Other manufacturers, including Hasbro, make lightsaber toys. These range from movie replicas such as the Master Replica versions to inexpensive plastic toys.
Kits
Corgi offers a build-your-own lightsaber kit. This kit gives a nod to the aspect of Jedi training where a trainee must make his own lightsaber.
Homegrown
The Wilcox family site has full instructions for building a lightsaber, including a full parts list. But any inventive Jedi could come up with something involving PVC pipes, luminous paint and imagination.