Soon Shine Sun
The Soon Shine Sun Shonky Shop has provided Ankh-Morpork's lower classes and the temporarily disadvantaged with previously (and thoroughly) worn fashions for many decades. "A genius when it comes to pricing fourth-hand schmutter", as the Sweeper states. The poor-but-proud would never buy from a pawn shop, but the shonky shop has the feel of a real store, even if the merchandise is worn very thin. His Grace the Duke of Ankh remarked that he set out to his first job in a suit from Soon Shine Sun.
The commonly unobservant populace does not notice that, although the shop has been there nearly forever, the proprietor has not aged noticeably. This is because Soon Shine Sun is also the History Monks' chef de mission in Ankh-Morpork. He usually takes no active part in their local activities, but remains undercover, providing a base for agents such as Marco Soto and the Sweeper.
The emporium's name also fills a gap between "She sells seashells by the seashore" and "The sixth sick Sheik's sixth sheep's sick."