Rural cemeteries with historic gravestones have become the target of thieves who peddle the folk-art sculpture to antique dealers for prices of up to $4,000, said New Hampshire State Sen. Barbara Pressly, who is sponsoring state legislation to combat the modern-day grave robbers. "They are irreplaceable items. When they are lost, they are lost forever," she said. Supporters of the bill, which would make it a crime to disturb burial grounds, told a legislative hearing last week that historic markers are being sold in antique stores, with some finding their way to plush high-rise New York apartments, where they are used as coffee-table tops. "It has been a serious problem and it has been getting worse in the last couple of years," Pressly said. "People who peddle the markers are robbing the state of its history and our heritage."