Go to Morrison's RX pharmacy in Plantation for 30 Nexium gastric reflux pills, and the list price is $202. Drive two miles to Costco in Davie, and it's $131. Unlike most products, the cost of medicine can vary sharply from store to store -- sometimes double or triple the lowest price -- as a result of the nation's complex and loosely regulated drug-selling system. LocalLinks Pharmacy industry experts say many people do not realize they can save money by comparison shopping, and that they can check a state Internet site that now posts prices of the most popular drugs from...