Actually, there is one more important parameter which can essentially affect the cost of a laptop battery. It is a manufacturer. As well as in any other area, the batteries made directly by a laptop manufacturer are called original/genuine, and the batteries created by any other company are called Generic or Replacement. Cost of the original battery and it Generic analogue can differ twice.
A lot of people think that generic laptop batteries cost much cheaper than original batteries because their quality is considerably inferior to the quality of original batteries. But it is not absolutely so.
As you remember, each battery is made of separate battery elements – cells. However laptop manufacturers are not engaged in the manufacture of these cells! They buy cells at other companies, and just assemble batteries from finished components. Precisely the same thing other battery manufacturers do, they buy the same cells at the same factories, and then assembly batteries and sell under this or that name/brand. In this case quality of generic batteries depends only on the quality of assembly, and has nothing on the quality original batteries.
As you understand, a laptop manufacturer will not risk their reputation; their batteries pass the most thorough quality assurance by manufacture. At the same time a no-name manufacturer can save money on quality assurance, and so the batteries made by this manufacturer will be inferior to the quality to the original ones.
So is it worth taking risks and buy generic batteries? The fact of the matter is that manufacturers of generic batteries also understand that buyers are suspicious of their production; therefore they not only sell them under lower price, but also provide longer warranty. So battery manufacturer Denaq gives 1 year warranty for all the batteries. At the same time warranty for Dell batteries makes 6 months. I would like to advise you to buy generic batteries, but the batteries made by known manufacturers who have already proved as reliable ones. I have already mentioned above Denaq company, the manufacturer of laptop batteries, cameras and video cameras. So if you search for the battery, get acquainted with their production.