Sprint and T-Mobile users rejoice! Now you, too, can have an iPhone without switching to AT&T or Verizon—cough, for the low-low price of $649. Apple has quietly begun selling unlocked iPhone 4s for that price online, Apple Insider reports. Pop in an active micro-SIM card and the phone should work on any supported GSM carrier. The only downside: Apple has specifically warned users that just swapping in their iPad 3G’s micro-SIM card won’t work. (More iPhone 4 stories.)