I don't know much about today's battery industry, and this comment isn't specifically addressed to the pricing policies of batteries, but related enough, I think. My grandmother used to work in a battery factory in Wisconsin (back when stuff was still made in the US...). They made blank batteries like the ones that fill the 6V, which were then wrapped in a variety of labels: RayOVac, Duracell, etc. WHich is to say, there was no difference in the batteries sold by different brands -- they were exactly the same, even though some brands were cheap and others expensive.

Since then, some new technologies have been introduced, like batteries specifically for electronics, that I assume are proprietary, so maybe this doesn't go on as much anymore (though I doubt it: like everything else, I'm sure batteries are made in a handful of Chinese factories that contact out to all the major companies).