So it depends on where you are. Shipment will be any more expensive than a battery from the factory was. If you have a card, it is best to buy on aliexpress.com There you first pay the money down in a Deposit, receive the parcel only after checking the goods and making sure that you are satisfied confirm payment.
In General, increased the batteries is the same brains with a larger number of cells. I do not believe in the promises of the sellers about grade A cells. Almost always lie :) of the cell is the biggest part of the cost of the battery and they save putting cheap Chinese. It is fraught with fire. Look on YouTube li ion fire, you will find a lot. Good batteries are also temperature sensors and fuses, but from the outside it does not see. But in General people take. Although the risk is there, but 90% of the defective battery is dead initially. Risk only the other 10%.
In the CIS countries almost always carry the nasty cells. Because of the price.
Immediately in order to avoid problems: denaq.com this is mine.