No one mentioned cost to me, these are the texts I got. I did ask them if it would cost anything when I called them, but they told me to wait until they had the car at Mt. Kisco to see what tires it came with. Yesterday a SA told me they came with summer tires.
EDIT: I was also told by Mt. Kisco today that they have to deliver the car with whatever tires it came with from the factory, and then I would need a service appointment to get them switched, which is the exact opposite of what I got texted yesterday.