China Unicom has reached an agreement with Apple to buy 5 million iPhones, with the first units set to go on sale in mainland China in September. Citing a CBN news article, International Business Times reports that the carrier has already paid Apple 10 billion yuan, or roughly $1.46 billion, for 5 million WCDMA iPhones, in both 8GB and 16GB varieties. The September rollout has been confirmed by Zhou Youmeng, vice general manager of China Unicom, who…