Don't pack bait, find it.What is the cheapest bait that will work?
For freshwater, go into the woods, flip over dead wood to find earthworms, crickets, or grubs. Flip over rocks in shallow water to find crayfish.
For saltwater, crabs, clams, muscles, shrimp, and small fish can all be found in shallow water.
Once you catch your first fish, gut it and use the guts as bait.
25' of fishing line, a few hooks of various sizes, and a couple of split shot for weight can easily be packed into a small container (35mm film containers work well)