I made some homemade muesli without raisins and other dried fruit. That seems to work quite well although I did add a few nuts. Too much bran is bad for you, although oats are supposed to be good for maintaining constant sugar levels. Its not all that cheap but it does last you a very long time
Ingredients:
Oats
Toasted wheat flakes
Wheat germ
Bran
Sunflower seeds
Pumpkin seeds
Linseed
Brazil nuts
Cashew nuts
Almonds
Desiccated coconut
Hazelnuts
Optional: raisins/sultanas/currents/chopped dates