For these kind of purchases, I have a credit card that allows me to credit virtual card numbers with a limit and expiration that I can set. I'll set the limit t

For these kind of purchases, I have a credit card that allows me to credit virtual card numbers with a limit and expiration that I can set. I'll set the limit to the order amount. If they try to charge more, the transaction is declined. That, along with the ability to contest charges (chargebacks), makes it a lot less risky.