LA MISION, Mexico -- Every weekend, Carmen Tetelboin joins the Baja boom. After work on Fridays, the Los Angeles resident drives four hours across the border to Baja California, where life is so good and living so cheap, it beats the other California, she contends. Owning a condo on the coast, she and her husband are part of an American colony exploding during the past five years along 75 miles of pristine beaches, cliffs and towns south of Tijuana. What's drawing them are oceanfront homes at a fraction of the multimillion-dollar prices on the U.S. side. A native of Chile...