How much work are you willing to do and how well stocked is your pantry? Bette Hagman, a prolific writer on gluten-free cooking and author of More From the Gluten-Free Gourmet (Canada, UK) offers two options, the most authentic of which involves making gluten-free Graham crackers first.
In the simpler version, which she calls Absolutely Sinful Cereal Crust, she mixes 3 tablespoons of melted butter or margarine, 2/3 cup of brown sugar, 1 cup of crushed rice bran, 1 cup of crushed gluten-free corn flakes, 2/3 cup of macaroon coconut, and 2/3 cup of finely ground walnuts. Mix it all together and line your pan. (Macaroon coconut, she says, is finely ground; if you can't find it, chop shredded coconut in a food processor.)
The more elaborate solution is to start making Mock Graham Crackers by mixing 3/4 cup of melted butter, 1/4 cup of honey, 1 cup of brown sugar, and 1 teaspoon of vanilla. In a separate bowl, mix 1-1/2 cups of brown rice flour, 1-1/2 cups of Hagman's gluten-free flour mix (more on that in a moment), 2 tablespoons of soy flour, 1 teaspoon each of xanthan gum, salt and cinnamon, and 1 tablespoon of baking powder. To make 1-1/2 cups of Hagman's gluten-free flour mix, combine 1 cup of white rice flour with 6 tablespoons of potato starch flour and 2 tablespoons of tapioca flour. Xanthan gum is a substitute for gluten (although bakers also often add it to wheat breads to improve the texture), and is available in many natural food stores or online.
Mix the liquid and dry ingredients together, adding between 1/2 and 3/4 cup of water, until the mixture can be formed into a soft ball. Refrigerate for at least an hour. In batches, roll out the dough until it is 1/8-inch thick, prick it here and there with a fork (if you like, you can dress it up with a pastry wheel to look like Graham crackers, but since you'll be grinding it up for a crust, don't waste your time), and bake it in the oven at 325°F (160°C) for 30 minutes. If the edges appear to be in danger of burning before the middle is done, break them off and let the center finish in its own good time.
Once the crackers have cooled, mix 1-1/2 cups of crumbs with 4 tablespoons of melted butter (half a stick), and add 1/4 cup of finely chopped almonds if you like. Press the mixture into your pan. The crust can be filled and baked, or used as is if the filling does not need baking.