Books are device-coded. I have Blackberry, iPhone, Kindle 2, K4PC and K4Mac, and they all have different PIDs. BTW I'm only missing android
The international prices are usually $2.00 higher than the american counterparts, regardless of transfer method. I guess that goes not only to pay international roaming fees but international licensing as well.
There *are* some cases where pricing is not the same as the US, here in Brazil I purchased Wolf Hall and The Girl Who Kicked The Hornet's Nest for less than the american version, two dollar fee included. Don't ask me why, but perhaps by some weird licensing it can happen, as the versions I have downloaded have British copyright texting. Also TGWKTHN was released earlier in here than in the american store. Covers are different as well.