i love the usa (and i dont live there) more than anyone i know. they get the MOST CHOICES, the most stores and the cheapest EVERYTHING all the time. and they dont even appreciate it most of the time. even their postage is cheapest. and they have TARGET. sigh.
however yes the THREE biggies i think of right away:
ITEM ONE
import taxes for you (in canada we are taxed on ANY ITEM that costs more than $20 as merchandise or $60 as a gift. yes i live in the third world)
ITEM TWO
ho is to say it wont break or malfunction during MORE shipping. and i doubt a warranty would cover it as a lot of documents say NOT EXPORTABLE OUTSIDE USA etc
ITEM THREE
yes your local mac place will likely NOT support a warranty etc for a product that is NOT allowed to be exported
to determine whether import duty is applicable to imported goods, Customs considers the following:
http://www.customs.govt.nz/importers/Commercial+Importers/Duties+and+Levies.htm