As rumors of Apple's budget iPhone continue to circulate, the U.S. tech giant has been pushing sales of its older iPhone 4 model in China as a way to grab market share in the nation's mid-tier market, according to research firm IDC.Related StoriesSamsung's next big thing - born in the USA?First Impressions of Apple's iOS 7CloudOn CEO: Office Mobile for iPhone is 'half-baked'
