Apple is already informing customers about early upgrade pricing for the iPhone 4S, even though pre-orders are only set to start on October 7th. For a Verizon iPhone 4 bought in February, for instance, a 16GB 4S is $649, while a 32GB model is $749, and 64GB is $849. Regular upgrade/new customer prices are $199, $299 and $399, respectively.
