I buy online once in a while. Mostly books and computer related stuff (the online markdowns for these items are usually worth the shipping wait and price). I did have one bad experience, but that was eBay and I did get my money back. The only thing lost was my time.
Although I do buy a lot online, I usually only use Paypal to buy stuff. That makes me feel a bit more safe because I only have to give my bank account number to one website.
Happy and safe shopping