I bought one. I think it was 13.50 with free shipping or something. I can provide an item number if someone wants it.
It came from hong kong or china and took forever. when I received it it would not power the phone. I charged it all night but never got anything more than a battery icon with a lightning bolt through it. I contacted the seller and he wanted me to ship it back to him and he would send a replacement, I told him it was not worth it for a 14 dollar battery, and I would leave negative feedback. he didn't want that. so he sent me a new one. I received the new one and it works great. its a slight bit thicker than the stock battery and it eliminates and looseness in the battery cover. over all it compares very well to the stock battery. have not had any issues with this one at all.
Curve 8520 184.108.40.2064