Sprint (S) has slashed the cost of purchasing and activating a new iPhone 4S by a total of $86 as the launch of Apple’s (AAPL) next-generation iPhone looms. Apple’s “most amazing iPhone yet” typically costs $199 with 16GB of memory, but Sprint has slashed $50 from the smartphone’s price tag. What’s more, online purchases will see Sprint’s $36 activation fee waived, lowering the total cost of purchasing the device by about 37%. Sprint has also cut the cost of the 32GB and 64GB iPhone 4S models by $50 each, and activation fees are waived for online orders as well. Apple’s sixth iPhone will be unveiled during a press conference on September 12th and it is expected to launch a week later on September 21st.