A gravity-feed bin includes a generally hollow main bin that has a storage reservoir and an open end. A first generally hollow extension section is selectably coupled to the open end of the main bin. The first extension section is in communication with the reservoir, and the storage capacity of the reservoir is increased by the first extension section. In some embodiments a seal element is intermediate the open end of the main bin and the first extension section, the seal element providing a substantially air-tight seal between the main bin and the first extension section. A plurality of extension sections and seal elements may be selectably coupled together in a stacked arrangement upon the main bin to increase the storage capacity of the reservoir.