Ethan has lightsabre props in his store, so Xander buys one, and gets Buffy and Willow to get two others, the rest being bought by various little kids (e.g., Dawn and Billy (from S1 'Nightmares') might go as Jacen and Jaina Solo).
Xander is Xan Dare, Jedi Special Forces, Willow is Wila Jade, Jedi Engineer/Inventor, and Buffy is Summer Daye, Jedi Healer (and devotee of the Sticky Side of the Force).
Of course, after the spell ends, they're going to have to set up a Jedi Academy in Sunnydale. :snigger:
EDIT: I've actually thought about writing this, or putting it up as a Challenge on XanderZone, before I found TFF. Still, this seems a good place to mention the concept, unless it deserves its own thread.