Cannot imagine how he gets a Note 4 for $250 with no contract and no service. If you find out, let us all know.
The price of a Note 4 at TMO is $749 + tax. They will finance it for you and accept money down as well--while you are on their service. They'll give you a phone, in other words, for $250, for sure, or even $0, but there will be a balance due and owing and it becomes due and owing immediately if there is no service with TMO. TMO is pretty reasonable about unlocking phones that are paid off, but I can't see how $250 accomplishes that.