Luke, Darth and Obi-Wan's Lightsabers were pieced out of junk piles. David shows you how to build exact replicas and an original design from The Custom Saber Shop. Then he picks a fight with Patrick.
Star Wars movie props and replicas are expensive memorabilia. Original pieces command a princely sum and replicas can cost anywhere from a $100 to a $1000 or more. For items like lightsabers, however, you can assemble your own replica using the exact same parts as the Star Wars prop makers. All you need is some time, an eBay account and a trip to the local hardware. Now if you want your lightsaber to be a bit more elegant and customizable check out The Custom Lightsaber Shop. Their Java tool will allow you to select and customize your lightsaber in almost any way imaginable.
If you wish to forgo the lightsaber in favor of something a bit more clumsy you can also build yourself a replica Stormtrooper or Han Solo's blaster. Since all those specific props were based on actual deactivated firearms you'll need to rummage through sites like Replica Weaponry.com and Aurora History Boutique to find decommissioned and replica firearms to base your blaster build on.