Cash

I would definately say PayPal, but then that would lead to convincing my mother to buy it for me. So unfortunately I choose cash.

cash..me no having paypal >.> though you shoudl've made a third choice, since cash would be annoying too, with me living on the other side of the world

Paypal....although I don't have one myself, plenty of my friends do, and from what I've heard it's extremely convenient if your country supports it. But if I were you I'd accept to both, because some people just don't have access to it (and you can make more cash!).

but do u have any other pay method than cash or paypal? because my poor little country didn't have any paypal's service beside cash is too riskT-T

I think paypal is generally the best but I think you should leave both open in case some kids don't have a credit card or bank account or don't wanna ask their parents to get a doujinshi or feel comfy explaining it. Or wanna pay themselves. But I think especially for overseas stuff Paypal is a safer and more efficent way to go.

No money
No credit card
No bank account
.........it's like I don't exist

I WOULD use Paypal, but I don't have it... XD