I'd strongly recommend a lithium battery set-up over a AAA one too (Obsidian V3/4).
Ah yes, batteries and a charger too. Forgot those. Good catch, Lord Rapine.
Cost wise, you may almost be better off just leaving it a stunt and ordering a saber with Obsidian. You're probably going to spend about the same amount or more. Unless you just want to DIY for the challenge, then that's a different story.
Before you get into a project of this scope, you may want to look at some how to videos on YouTube.