Camping often includes backpacking, and the most important item when you go backpacking is the backpack. Backpacks need to fulfill a variety of functions. They need to be big enough to carry everything necessary for the trip, including bedding, food, water, tools, shelter, and a jacket. They need to be large enough to distribute the weight evenly, and have wide, padded shoulder halters so the weight can sit comfortably on the back. They should be sturdy and not break easily. They should be waterproof, so if you are caught in some sort of storm, all of your gear is not destroyed. You need something resilient, dependable, easy to use, and the right size. All of that doesn't always come cheap, and backpacks can seem expensive, but that's only if you don’t look at them as an investment you are making in your camping future.
Backpacks are available through various vendors. You can find them in big box stores or department stores, like Target. They might be a bit cheaper, but typically, the selection is not the best. You can also find them through sporting goods stores, where the price might be higher, but so will the selection, and the sales people might be a bit more knowledgeable about what you will need. You can also find them through online vendors, which has the added bonus of often having user reviews on the page. Reviews can help you narrow down your choices, especially if you are purchasing your first one and you don’t have much experience with the various brands.