Used eaaypaisa Virtual card for AliExpress so far. Works flawlessly. Use dollar rate 110 for calculating ur item cost (I calculated including their charges and their conversion rate).
Have yet to use on eBay/Amazon. But I'm sure it'll work.
Just download easypaisa app and make ur mobile number ur account (MAKE SURE MOBILE NUMBER YOU USE IS IN UR NAME). Then transfer money into it from atm or easypaisa shop or from bank (online banking transfer isn't working for me yet). Then make ur virtual card from the app (it's instantaneous).
Then ballay ballay.