Two major things to watch about EBay. Do not order things from overseas, particularly from Hong Kong or China. Even if they are reputable, it's very hard to send things back and more than once I've had problems. Another, look at a person's feedback. If it is high with very few strikes against them that is a good sign that what they are selling is probably gunuine and that they are reputable. With Pandora charms, I don't know if there's a counterfeiting market or not, but if a dealer is in the U.S. and has a good reputations it's probably okay. Why are they so much less expensive? Could be a lot of reasons. A merchant could be overstocked with them and is just trying to sell them at cost, or it can be a private seller who no longer wants his bracelet and charms or needs the money. No telling, but if their reputation/feedback is good, they are probably the real thing. Good luck.