All orders are processed in SGD. The currency converter is merely a convenient tool for your easy reference only.
The only mode of transaction is through PayPal. If you don’t have a PayPal account and intend to never have one in this digital age, you can also do a one-time transaction through PayPal with your card details. And no, we don't store any of your card details, it all goes through PayPal's secured gateway. Ask them.