Losing PR staff to competitors offering more bountiful stock options has become a rite of passage for most employers. But the greenest grass luring pros away from the nest: entrepreneurhood. International Data Corp. reports a free agent/telecommuter population of about 41 million in the U.S., and expects the species to proliferate to over 51 million by the year 2002. The economy is ripe for PR start-ups. "We are in a remarkable time of new business growth," says Terri Lonier, CEO of Working Solo, Inc., a New York-based firm that provides strategic advice to companies targeting the SOHO (small office/home office) market. "When new companies are formed, they realize they need services like accounting, advertising and public relations. There's a spiral growth that occurs, where new business ventures spur other [service-related] new business ventures."