Almond flour = almond meal = ground up almonds.

Many health food stores or bulk stores sell them. BUt I can't believe that almost every ordinary supermarket wouldn't have some form of almonds for sale. Look in the "baking supplies" aisle. If you find them whole or slivered, then just put them in a blender and give them a few pulses at a time. Don't blend too much or you'll have "almond butter".