Plan to Shop
If you are going to be traveling for more than a few days, you will need to stop to shop for provisions. You will also need to pay for those provisions. Be sure to carry enough cash or checks to pay for restocking your pantry or you may find yourself going hungry. Some large grocery stores do accept credit cards for purchases. Many smaller stores may not take credit cards and may not accept out-of-state checks (this will vary from place to place).
While prices may not be the most important thing you look at when shopping for food supplies for your travels, there are some things that you can do to save money. Prices on most items will generally be lower in large chain stores than in smaller independent grocery stores. You may also find lower prices in larger urban areas with many stores and more competition for shoppers. One exception is fruits and vegetables in season. Look for roadside farm stands selling fresh-from-the-field goods. Prices are often much better than in supermarkets, as is the quality.
You should also shop carefully for the freshest meats and produce you can find. Your RV refrigerator is not as efficient as the one at home, and fresher foods will last longer in it.
If you are traveling with a group or with friends, you may want to take advantage of cost savings of larger quantity buys. While not everyone will need the same things, there may be items such as rice and beans that can be purchased very economically in large quantities and divided for all-around savings.
Unfortunately, you may find the overall cost of some items is higher because you are not buying them in bulk while you are on the road. With the limited storage an RV affords, getting a bargain on that twelve-pack of paper towel rolls from the shopper's club (or even buying a value-priced jumbo bottle of ketchup) is not a realistic option.