When high-school sweethearts Alicia Gomer and Mark Wittink got engaged in December 2001, they pledged that their wedding would reflect their commitment to ecological issues. Gomer, who is working on an M.S. in environmental science policy, and Wittink, a project director at the Resource Conservation Alliance in Washington, D.C., were "shocked at the lack of green options in wedding planning. We had no idea what a consumptive, high-impact industry weddings can be," Gomer says. About 2.4 million couples get married every year in the U.S., at an average cost of $20,000 per wedding, generating total revenues of some $70 billion, …