interesting topic, sorry I can't help personally but I'm interested on the logistics of such a transaction
obviously it would not be smart to stuff a brand new computer, sealed in its original box in your checked luggage... damage, theft, etc. not worth the risk
taking it in a carry-on would require opening it (taking it out of the box) at the security screening, which would make TSA wonder why you're carrying a laptop in its original packaging... which isn't an issue, but the customs on the other side may ask about the value of purchased electronics which need to be declared I'm sure (is there a tax you pay upon arrival?)
I don't know about Apple, but places like Dell specifically ask you if the computer/camera/electronics you purchase will remain in the United States... I seem to remember something like that, a question specifically asked if the item will be used for export.
So just for my own good, I'm curious how does it work to deliver this favor as hassle free as possible?