The official retail website of the Boy Scouts of America at www.scoutstuff.org sells a variety of patches in the category labelled Uniforms and Insignia. They also offer a store locator capable of finding retail brick and mortar stores that sell Boy Scouts of America products.
The BSA website sells all types of uniform pieces, not just patches -- pants, shirts and accessories are all available for sale. Badges are found under the category Insignia Cloth and further sorted by whether the badge is required, earned, awarded or obtained in some other way.
The store locator allows a user to search for stores by address, city, state or ZIP code. Search results include scout shops and council shops, as well as other stores that sell official Boy Scouts of America merchandise.