There’s nothing wrong with buying a prepared pie crust, but it’s so easy to make your own that I urge you to do so whenever possible.
Put the flour, shortening, sugar and salt in the bowl of a stand mixer fitted with the paddle attachment. Paddle at the lowest speed, just until the mixture holds together, about 30 seconds. (You can use a hand mixer if you allow the shortening to soften at room temperature before beginning.) Add 6 tablespoons water, and paddle until absorbed, about 30 seconds. If the dough seems dry or fails to come together, add the last tablespoon of water.
Transfer the dough to a piece of plastic wrap and refrigerate for 30 to 60 minutes.
Lightly flour your work surface, and roll out the dough to a circle about 14 inches in diameter, about ¼ inch thick. Roll it up onto the rolling pin, and transfer to a 9-inch pie pan, unspooling it over the top. Tap the pan gently on the work surface and the dough will fall into place. Put your hands at the 2 o’clock and 10 o’clock positions on the side of the pan, and rotate the pan from just under the lip to cause the excess dough to fall away. (If molded in an aluminum pie pan, the dough can be wrapped in plastic and frozen for up to 2 months. Let thaw to room temperature before filling and baking.)
Note: If you are making this in the summer, use 6 tablespoons water to account for increased humidity affecting the moisture content of the flour.