There is an official contract-free unlocked U.S. iPhone 4 source now: The Apple Store. The 16GB model costs $649 while the 32GB model is priced at $749. Both phone models are available in black or white.

iPhone 4 – Unlocked (GSM) – 16GB Black

These unsubsidized contractless devices come without a microSIM card. Buyers will need to get a microSIM card from their GSM carrier. Apple confirms that the unlocked iPhone 4 can work with microSIM cards provided by carriers outside of the U.S.

Apple does not disclose which GSM carrier’s 3G network the unlocked iPhone 4 is turned for (AT&T or T-Mobile).

A tip of the hat to PCMag.com Editor-in-Chief Lance Ulanoff for breaking the news on Twitter.