I understand where you are coming from, but I am currently using SolidTrustPay, and they are a very secure site. You have to sign their form in order to use a credit card. The information is sent through email, but if your email is protected and your credit card company protects you from fraud, you shouldn't have anything to worry about.
SolidTrustPay takes security very seriously, since they require many different passwords and a PIN, so I am sure you are safe. If not, I know many other websites use AlertPay and other payment processing websites.