I agree that there are scammers everywhere. But one of the reasons for forums like this one is so that people can get opinions and reviews on products from those who actually USE them... not just blind opinions.
The OP asked about batteries. The posts, including mine, have replied with first-hand knowledge of products we actually use, are happy with, and have a educated opinion of. That is appropriate. Others, who pooh-pooh the use of anything other than OEM products haven't claimed in ANY of the posts here that they have used third party batteries that have either damaged, or otherwise been a bad purchase. So that makes those kind of posts sound specious, and simply elitist.
Let me again rephrase my point:
This has nothing to do with being "elitist". In fact, I'm usually a pretty cheap bastard. But sometimes being successful at being "cheap" means doing it right in the first place. With these batteries there are essentially four choices:
1. Buy whatever from any Chinese vendor on ebay
2. Buy third party from known dealers after doing the research
3. Buy cheap "original" from the guy in #1
4. Buy Canon from a Canon authorized dealer
Chances are, #1 and #3 are junk and you get ripped off. Chances are also that #2 and #4 may (!) actually be the same exact battery from the same Chinese factory with some kind of Japanese quality control in place. What you are paying extra for in #4 is basically some kind of insurance in the probably rare event that the battery destroys your camera - assuming that you keep your receipt etc.
Buying "Canon" from some guy on the web or from a corner store runs the risk of getting one of the many many fake batteries out there. It may not even be a scam on part of the seller. They may just not know. Same thing could actually happen at an authorized dealer I suppose. Counterfeiting has become a serious problem. Talk to people in the pharmaceutical industry where stuff gets swapped along the entire supply chain. There are estimates that 1 in 4 medications are fake.