used to make my own trail mix,
go to the bulk section of the local grocery store, load a bag up with nut mix (walnut, almond, macamadamia, cashew, brazils, pecans)
dried; banana, papaya, mango, coconut, dates (but no friggin raisins, hate raisins, which is why i was making mix instead of buying it prebagged, not to mention it was cheaper, raisins, feh!)
chocolate chips (white/regular/peanutbutter) or mm's
and one of those 'camel paks' half filled with ice, topped off with water
now, i carry a fair selection of lo-carb meal bars, handy and fairly price effective compared to airport food, granted not as tasty as my old mix bag of stuff, but it does the job