Bearproof is a difficult standard to meet. You might look at government surplus ammo cans, but they would be steel, heavy, surprisingly expensive, and probably not nearly large enough.

May I suggest that your vehicle is probably sufficiently bearproof and storing your non-perishables in a non-certified container inside your vehicle would probably be both cheap and effective. Very few bears have learned how to open car doors or windows and the only ones I have heard of live in CA, not GA.