2-3 days ago I ordered 3 book from Amazon instead of PokerStars, because you're paying ~$32 per each(!) in Stars VIPshop (0.016*2000)...
It's the same price I'd pay for courier delivery from USA to Slovakia (in 2-3 days) and it's 43% more then for Amazon standard delivery fee (including book of course

)
It's up to you, but personally I prefer cheaper option