Spare key for 2015 Sierra

[mjager]

Anyone know how much one would be from GM? Is there other alternatives?

[newdude]

$43.86 from your dealer for a cut one if they don't have the machine to cut it. They order it from GM with your key code and they take a day or two. If they have blanks in stock and the correct machine to cut them, they may charge you more if they have to look up the key code from the VIN. You should have the code in your possession.