I'm not sure about using a credit card for this.
Simply put, credit cards are usually issued to (high-level?) employees that leave, change contact details, etc... so your customer lifetime value is capped by the credit card expiration date.
I've seen bills coming for backup ISDN lines located in offices dismantled several years ago. Why? because the cost was small and it was already pre-aproved in the budget.
Only after a huge review we found out cases like this. But, that kind of reviews are unusual and expensive.
If you can afford to invoice a company and make them pay the bills for small quantities, you've got a business.
I do agree that low cost is a bad idea to start with, unless you can own all the market and start raising prices... BUT in that case you open easily the door to new competition and since your customers are price sensitive, you're asking them to churn as soon as possible.