You guys might wanna just make sure your computers are secure - no adware, no phishing, no weird little bots, blah blah blah...or get a mac. Not foolproof, but a little bit safer than PCs...
You also may want to make sure you're not responding to Phishing emails. I got one a few years ago that looked just like it was from my account on ebay, at the time it looked like a potential buyers question (and a fairly legit one ...even about something I DID have for sale...unlike most of them). Well, turns out they hijacked my ebay account!
Now when I get emails about any account, I ignore the emails and log into that account to check.
I'm a seller (mostly books and other media) and my merchant account on my website is very secure. Have never had any problems with customers having account info stolen. There are alot of safeguards in place these days...much more than there were even 10 years ago. And I have no access to the buyers info after the transaction goes through. Most websites that sell are setup like this, they HAVE to be. A few years back anyone who has a merchant account has to go through a whole PITA process called PCI compliance in order to check these safeguards quarterly.
I'm not saying that all sites are perfectly safe, but the majority more than likely are perfectly safe.
Typically most accounts are compromised from phishing emails or a larger bank entity where many accounts are stolen at one time, not necessarily the website itself, unless the site is a scam in itself.
But still, Shame that there are fools out there that think it's their right to steal from others!