Just like buying anything else from the internet, it's gonna depend on their reputation. Obviously the bigger the name (Summit, Jegs, Speedway, etc) there shouldn't be a problem. But some small name shop, unless it's local to you or someone you know and can trust their opinion, can be hit or miss. So far I've had really good luck with anything I've gotten through online retailers, even through Ebay, you just have to do your due diligence. But I'd think that most semi-reputable businesses wouldn't knowingly sell you some piece of crap either online or in person, but there are those out there who are only looking to make a quick buck from some unsuspecting "fool." It's just good business practice to build a customer base if you want to succeed.