What started as a rumor has now become a reality with Apple now offering either the 16 GB or 32 GB iPhone 4 unlocked from their US Apple store site. The 16 GB costs $649 in either black or white and the 32 GB is retailing for $100 more at $749. If you don’t want a multiyear service contract or if you prefer to use a local carrier when traveling abroad, the unlocked iPhone 4 is the best choice. It arrives without a micro-SIM card, so you’ll need an active micro-SIM card from any supported GSM carrier worldwide. If you want to learn more about the differences between locked and…