I actually think that this would work well to make my own mix if I wanted to. I would just measure out the dry ingred. and bag them, bag the streusel ingred. separately and if I add the butter, freeze them, then all I would have to do when I wanted fresh muffins is to add the wet ingred. and bing I'm in business. I found this recipe on Allrecipes.
To Die For Blueberry Muffins
1 1/2 cups all-purpose flour
3/4 cup white sugar
1/2 teaspoon salt
2 teaspoons baking powder
1/3 cup vegetable oil
1/3 cup milk
1 cup fresh blueberries
1/2 cup white sugar
1/3 cup all-purpose flour
1/4 cup butter, cubed
1 1/2 teaspoons ground cinnamon
1-Preheat oven to 400 degrees F (200 degrees C). Grease muffin cups or line with muffin liners.
2-Combine 1 1/2 cups flour, 3/4 cup sugar, salt and baking powder. Place vegetable oil into a 1 cup measuring cup; add the egg and enough milk to fill the cup. Mix this with flour mixture. (whoops, I mixed the dry ing., then dumped the wet all in at once.) Fold in blueberries. Fill muffin cups right to the top, and sprinkle with crumb topping mixture.
3-To make crumb topping: Mix together 1/2 cup sugar, 1/3 cup flour, 1/4 cup butter, and 1 1/2 teaspoons cinnamon. Mix with fork, (I use a pastry blender, not a real blender, that hand held thingy that looks like it could slice a hard boiled egg), and sprinkle over muffins before baking.
4-Bake for 20 to 25 minutes in the preheated oven, or until done.