U disk can be purchased in digital stores, computer stores, brand stores and other physical stores. Digital stores usually specialize in selling all kinds of digital products and accessories, including USB flash drives. Computer stores are also common places to buy USB flash drives, because they usually provide various computer-related products and services. In addition, some brand stores will also sell USB flash drives. These stores usually specialize in selling products of a certain brand, including USB flash drives. So if you want to buy a USB flash drive, you can go to digital stores, computer stores and brand stores.