Small charges get drowned in transaction fees. Better to do $12 per year. You can also charge based on usage, and just run up a tab, where they are only billed

Small charges get drowned in transaction fees. Better to do $12 per year. You can also charge based on usage, and just run up a tab, where they are only billed at the end of the payment cycle if they have exceeded a minimum amount. Like Google AdWords, but in reverse.