Bich Ngoc, who earns less than $60 a week and has a newborn son, cobbled together four months of savings to buy the latest iPhone so she could impress her colleagues who have older versions of the device. “I like the iPhone because it is small, light and very delicate,” said Ngoc, a 24-year-old accountant in Hanoi who purchased the device last week. Apple Inc. (AAPL) is looking to consumers such as Ngoc in Vietnam and across Southeast Asia willing to spend more than two months salary on an iPhone or iPad, as it seeks sales amid competition with Samsung Electronics Co.