Buy.com seems to be buying iPhones from foreign countries where it hasn't been locked down to a specific carrier, then selling them in the US for $US800.
The sales description says that these phones work fine with software updates—something software unlocks don't—but your instructions may come in a language that's not English. That's a small price to pay for an unlocked iPhone. A big price to pay? $US800. [Buy via 9to5Mac]