A small budget yields big commercial appealMelissa Tan wasn’t sure what the response would be to Little John’s Derby Jewelry’s first-ever TV commercial in 2011: an intentionally campy spot featuring a woman stuffing gold ­jewelry into an envelope. (The message: Don’t mail your gold—bring it in for cash.) She wrote and produced the ad, hiring a local crew to film it for $3,000. It paid off “almost instantly,” says Melissa, who co-owns the Louisville, Ky., store with her jeweler husband, John “Little John” Tan. Melissa and her crew kept making commercials—budgets grew as business improved—always starring a straight-faced John and purposely corny songs and characters, including grown-up Christmas elves, Village People and Michael Jackson impersonators, and the recurring Super Gold Man, a burly local guy in a shiny blue superhero costume who delivers customers to Littl