While modern grocery stores can be found in larger cities, these can often be far apart. In smaller towns, fresh vegetable and fruit markets are seldom open everyday, most only once a week. We picked up the habit of buying food in large quantities. We stock many types of whole grains (buckwheat, whole wheat, cornmeal, oats). Different grains offer different nutritional profile, and meal options.
Canned, dried or shelf-stable foods are a good alternative to refrigeration. Choosing canned foods is something worth experimenting with. Buy an assortment, find ones which suit your tastes. We usually look for unsalted ones, without corn syrup.
Our favourite canned vegetables are mushrooms, mixed beans and tomatoes. Our favourite dry foods are nori, oats and cornmeal. Our favourite shelf-stable foods are tetrapak tofu, spicy sauces and various japanese condiments.
We buy flour in bulk, and keep it separate jars (each accommodating a 2 kg bag). Keeping some types of flour separate helps to avoid problems, like weevils. If one batch is contaminated, the other might be fine.
Provisioning can be expensive in certain countries, so stocking strategically with cheaper stores, ahead of time, can help to save money. If you're shopping and you see something you like at a good price, buy tons of it; chances are you won't be seeing it again on your next visit (turn-arounds are quick in some stores, and won't re-stock the same items necessarily).
Preserving food, via lactofermentation, or canning, is essential when traveling on a budget. A pressure cooker and glass jars will too save you money and will help reduce waste. Preparing your own stores, also means that you choose what goes in it, therefore reducing your intake of added salts and sugars.