Espresso Powder, Anyone?

I need help. I want to make these brownies:

Espresso Brownies Recipe courtesy Giada De Laurentiis

Nonstick vegetable oil cooking spray
1/3 cup plus 2 tablespoons water
1/3 cup vegetable oil
2 large eggs
2 tablespoons plus 2 teaspoons espresso powder
1 (19.8-ounce) box brownie mix (recommended: Duncan Hines)
3/4 cup semisweet chocolate chips
1 teaspoon vanilla extract
1 1/2 cups powdered sugar
1 tablespoon unsalted butter, room temperature

Preheat oven to 350 degrees F.

Spray a 9 by 13-inch baking pan with nonstick spray. Whisk 1/3 cup of water, oil, eggs, and 2 tablespoons espresso powder in a large bowl to blend. Add the brownie mix. Stir until well blended. Stir in the chocolate chips. Transfer the batter to the prepared baking pan. Bake until a toothpick inserted into the center of the brownies comes out with a few moist crumbs attached, about 35 minutes. Cool completely.

Meanwhile, dissolve the remaining 2 teaspoons of espresso powder in the remaining 2 tablespoons of water in a medium bowl. Whisk in the vanilla. Add the powdered sugar and butter and whisk until smooth. Pour the glaze over the brownies. Refrigerate until the glaze is set. Cut into bite-size pieces. Arrange the brownies on a platter and serve.

But I have no idea where to get espresso powder. I have looked in the grocery store and all I find is espresso coffee, not powder for baking. I've been looking online but I have come across just about every carnation of coffee from beans to butter that there is. And needless to say I'm confused. Any recommendations? Advice? Thanks.

Sweetpiv