Shield Shop

The Dark World Shield Shop can be found directly west of the Pyramid of Power, and east of the Village of Outcasts, in A Link to the Past. This shop is completely fenced in, with its only access point along the Northern perimeter. Link must jump a series of fences to even get in.

GBA version
In the Game Boy Advance version, the Dark World Shield Shop sells nothing except for shields. Like Likes were not in the original release of A Link to the Past, but in the GBA re-release, they can be found outside the Shield Shop, which is advantageous for this particular business. The Dark World Shopkeeper won't sell Link any shield inferior to the one equipped.