i used QNB you can use any banks credit card as long as its a credit card :) you just link it to paypal and then you are good to go.. you can get from sidewindercomputers couple of good sellers in ebay you can buy from in bulk and will give you discount and amazon frozencpu performance-pcs etc alot of shops but these are the ones i used :)

tigerdirect has a seller in ebay i dealt with him he was good in communication ;) dunno about the website

the cheapest you can find anywhere is newegg but they don't accept international cards