It is the right box with what I wanted.. they do sell internationally but they only accept bitcoin apparently. Which makes me feel unsafe
Consider how much risk there is. You only expose the amount of cash needed for the purchase - IF you get a prepaid Visa card holding the exact amount needed to cover the purchase (and whatever fees the card-issuing company charges). It's a matter of how comfortable you feel risking even that amount of cash. Done in this manner, you have no exposure in terms of your credit card or debit card or bank account numbers - prepaid cards are practically disposable. The only added cost is an activation fee - think of it like paying for insurance.
Either that, or try talking the guy into taking other payment, like PayPal or Amazon Payments. Not everyone likes them, but perhaps you can persuade him. Sellers tend to like it the least, but that's largely because of how much they protect the buyer, usually ruling in favor of the buyer in disputes.