Walk past the twirling yellow Ferrari and tilting silver Porsche. Cut through the rows of designer knockoffs, Bob Marley beach towels, and assorted ninja weapons. Then hang a right toward booth AA24, a shimmering beacon of dental cosmetics plopped in the melting pot of Fort Lauderdale — the Swap Shop. Sure, it's a bit weird to seek out minor dental procedures in a sprawling flea market, but it's tough to find a better deal when it comes to getting your pearly whites pearlier and whiter. For $60, the folks at Celebrity Bright Smile guarantee to whiten your teeth by two shades in just 20 minutes. The trick? A substance called carbamide peroxide. Brendamarie Canfu, the round-faced sweetheart who works the stand, says most dentists use the substance in a concentration ranging only from 25 to 35 percent. At the Swap Shop, Canfu and her colleagues will slather a 44 percent concentration of the stuff across your chompers. Though we have no idea if the more potent concoction actually makes your teeth glisten any brighter, Canfu says it can't be used on pregnant women and people with pacemakers. That must mean it's good.