I've had difficulty with my order and it still hasn't gone through yet. I ATTEMPTED to pay for it with my Mastercard...it took me to a payment site, where I entered in all my data, but when I clicked on the Mastercard logo, the credit card number field disappeared.
It took me to a separate payment site through the Bank of China which didn't allow me to select my credit card.
Currently, it shows my order on PopBuying as a "Quotation Created". When I click on the payment link, it takes me to they payment site where it says "Delivery address country parameter is illegal.", which makes no sense at all.
I actually preferred Paypal myself, as it took care of all of these things in one convenient site, plus all your information (shipping addys, credit card info) was not spread all over the place.