(not trying to be a dick - this is me trying to help others to learn from your experience)
This is yet another person learning the hard way that cell phone batteries that are the same size won't have a higher capacity and definitely do NOT command a premium price. If they're cheaper than OEM batteries, then go for it as a way to save money, but never expect one of these to be better than a new OEM battery. Better than an old OEM battery that's losing the ability to hold charge, definitely. But better than a healthy OEM batter, no way!
I'm sure there have been some rare exceptions and will continue to be (rare exceptions), but this is the general rule of thumb to go by and is what to expect. Any time you pay premium for a battery the same size as OEM, expect to be wasting your money. If you go into it with any other expectations, then you have unreasonable expectations. After all, what are your expectations if you buy a Rolex from some random guy on the street? If you really expect to get an authentic and non-stolen Rolex, you have unreasonable expectations. That's all these "extended battery" companies are - people breaking the law to screw you over. Go into it with the proper expectations.
(Those who lie about the capacity yet only charge $20 for 3 batteries + charger, well, perhaps they're breaking the law but given that you're getting the batteries at a discount, it's somewhat "moral". But lying to you while charging you double, well, that's just wrong.)