<<For this iPhone I have $9 in my account>How much money I have to add>>
As with any purchase, you need to have sufficient funds to cover the total cost. If you buy in Canadian dollars you will have to consider the conversion cost if it is listed in US dollars, the item price, plus shipping. If it is a GSP item, do not overlook the added import charges that will be present at the checkout as well.
Or of you have a credit card burning in your wallet, you can whip it out and go through the checkout with the item right now (or add the card to a paypal account) and then pay the card balance later, - either online or when you are at your bank in person.