Ask HN: How do you handle chargebacks?

I am launching a startup soon. The most pressing problem is how to collect money. The fine print at Google Checkout, PayPal, and WePay indicates chargeback fees of $10, $20, and $35, as well as language to the effect that even a single chargeback could result in my account being frozen or closed. I don't mind the occasional chargeback, if a person genuinely could not get satisfaction from me, but I wonder if this could be a way for a competitor to attempt to shut down my business. I'm not saying that this is likely to happen, but it has occurred to me that a competitor could simply purchase a number of prepaid credit cards, and use each, from its own email address and IP address, to make purchases from my website, and then, for each purchase, complain to my credit card processor that I've done a lousy job in servicing their order. I'm not trying to be paranoid here. I honestly don't know how to make it easy to accept credit cards while avoiding the potential for such a situation. Thanks, in advance, for any useful suggestions.