The Technomancer 2.0 Digital Wizard Hoodie is a $120 hoodie available from ThinkGeek (previously an April Fools' joke that they made real). The hoodie has accelerometers in the sleeves programmed to read nine different spell-casting arm movements, each one of which produces a unique color glow from the sleeves and hood, along with a sound effect from the integrated speakerbox. The spells include Electroshock, Thunderbolt, Restore Health, Fireball, Shockwave, Energy Beam, Raise the Dead, Warp, and Water Bending. Apparently some of the spells take time to master though, so don't be surprised in the beginning if you're constantly raising the dead when you're trying to restore health. Also don't be surprised if people stop to ask if you're okay and if your parents know you left the house without supervision.
Keep going for a couple more shots and a video of a guy demonstrating all the spells, then put on your robe and wizard hat.
Thanks to Twoheads, who is allegedly better than one although I bet not at saving money on hats.