When I was a kid, I'd wear an old bathrobe I found in a closet as a Jedi robe. I'd pull out my plastic lightsaber and battle Sith lords in my backyard. In a neat extension on my childhood Sith wars, Lucasfilm is now marketing an actual bathrobe that's Jedi-style, and it's kinda cool.
It's a one-size-fits-all affair, is made of cotton velour, and features an awesome Galactic Republic logo right over the heart. It's $70 on preorder right now, and it ships in November.
You'll have to come up with the rest of your Jedi outfit, as it doesn't include duster boots, a lightsaber, or anything else. But if you're nerdy enough to get as geeked about this robe as I am, you probably already have all that, don't you?
And if the light side of the Force isn't your scene, there's also a badass Sith robe, you evil despot you.