So i've been gone ofr a while but this summer ship sale has me intrigued. I went to buy more but I got sent to the Perfect world site. I'm confused, do I have to buy Zen first and then transfer it? Why can't I just buy it directly from Cryptic?

What are the payment options? Do I choose from, 100 zen for $10 or 500 zen for $25?

I am so confused right now and I hope someone could help me out.