On: How to Be Persuasive

At the risk of killing you, http://www.aonevitamins.com/caffeine.htm , which is simply the first hit for "caffiene powder". It's not exactly a tricky recipe.

United Nuclear has it cheaper. http://www.unitednuclear.com/chem.htm

Just, yeah. Don't kill yourself. :P Lethal dose is somewhere between 10 and 20 grams. Rough, spydez-levels of caffeination call for ~1/2 teaspoon of pure caffeine powder per gallon of water or juice or tea or what have you.

Enjoy.

Or, for extra credit, make a caffeinated heavy water ice cube.