On the AT, food resupply is not an issue, and food is cheap, especially in the southern states. In the New England states, it is more expensive, but everything is more expensive here. Beside the shipping cost, you have to factor in the cost of shuttles from the trail to towns and back because your box will be waiting for you either in the PO or a hostel or a outfitter. Now days, most town have a local supermarket, and if not, you can always get a shuttle to the local walmart or whatever big box super market they have.