Right, Crysta is unfortunately only available in certain countries as a payment method for FFXIV subscription (Australia where I live is one place that it isn't available for, I found that out the hard way back in 2010 when I first signed up for FFXIV version 1.0 ).

Sadly there is no way around it. All you can do is use an alternative payment method like a prepaid time card (sold by certain online retailers) or a credit card/debit card.