Stamps man be purchased from any United States Postal Service retail location at the counter, and some locations offer vending machines that are available outside of normal business hours. Many grocery and retail stores now sell books of stamps as well.
Purchasing a single stamp, less than a full book of stamps or a stamped envelope requires a visit to a post office retail counter. Books and sheets of stamps can be purchased at many different retail locations.
Many of the major retail, grocery and office supply chains carry books of stamps. They may be purchased by asking a clerk for them at the cash register or at the customer service desk. Some examples of nationwide chains that carry books of postage stamps are CVS, Office Depot, Walmart and Walgreens. Many regional chains and mom-and-pop locations carry them as well. Other potential sources of stamps are banks, gas stations and ATMs. Not all will carry them, but some do.
Books and sheets of stamps may also be purchased online at Amazon. Printable postage labels are also available for purchase online through the USPS website, though this requires weighing the letter or parcel at home to determine the accurate weight before purchasing.