With a signed two-year pact, you can buy the Glacial Silver HTC One (M8) for $199.99. Those using AT&T Next 12 can purchase the phone for 20 monthly payments of $32 ($640). Those on the AT&T Next 18 plan will pay 26 monthly payments of $24.62 ($640). If you want to shell out the full retail price with one fell swoop, it will cost you $639.99.
Expected up next for the HTC One (M8) line is the HTC One (M8) mini, which is due out next month in Europe and Asia. Eventually, the device is expected to be offered at Verizon, and perhaps other U.S. carriers as well.
source: @HTCUSA, AT&T