there is no way.. at&t is gonna give u the subsidy code for an iPhone. the new iPhone will cost T-Mobile customers about - $375- $400..- ($199.00 with new 2yr activation and $175 or $200 for terminating the contract) n then u hav to wait for some nerd to unlock it. ( which could be a month or two, start July 11th)..
  all in all $375 isn't too bad for the iPhone.
---- check out the white iPhone 3G.