Natural foods stores
Natural foods stores usually have a bulk section, where you can buy as much or as little of various dried goods as you like. Selections typically include dried fruits, nuts, trail mixes, granola, other dry cereals, rice, beans and lentils, spices and dried herbs, powdered milk, flours, and grains. Some also have prepared dried-soup mixes in bulk bins or packages. Other handy foods for camping include jerky, freeze-dried fruits, fruit leather, and snack bars. In many cases, organic and/or locally sourced options may be available.
Trader Joe's is another good source for dried fruit and nuts, as well as snack bars, jerky, and freeze-dried fruit. World Market (formerly Cost Plus) also has a variety of packaged and dried foods, including soup mixes.
Camping stores are great places to get prepackaged, complete dehydrated meals. Chances are you need other items for your trip as well, so this can be your one-stop-shop. You will probably pay more for the convenience, but it may be well worth it if you are short on time.
Dehydrated and freeze-dried foods are available from many Web sites, from general outfitters like REI to those that specialize in survival/emergency preparedness or backpacking food. Sierra Trading Post often has prepackaged backpacking meals on sale, though their selection may be limited. Since prepackaged dried food typically has quite a long shelf life of 1 to 7 years, consider stocking up when you find a bargain on a brand or flavor you like.
If you have a food dehydrator, either electric or solar-powered, you can easily make your own dried fruit, vegetables, and even jerky. Drying your own food is fun, and a great way to preserve fruits and veggies when they are plentiful and less expensive. It also gives you total control over the source --- organic, local, or other. Be sure to follow instructions carefully to avoid food spoilage, especially if making jerky. Food needs to be thinly sliced. Fruits and some veggies can be dried raw, like tomatoes and bell peppers.