I will second the notion that indeed AA batteries, whether Alkaline, Lithium, or Zinc Carbon, for purchase by consumer at a super-market checkout, have not gone cheaper recently.
I will even venture that consumer lithium-ion batteries, such as for camera or laptop replacements, do not appear to have gone cheaper over last, say, decade. I can only assume healthy profit margin by brands (Nikon/Sony/Canon/etc, Lenovo/Sony/Dell/etc). Third party cheaper batteries are available, of dubious quality, so I suppose that may be a sign of cheaper manufacturing...
I'm not quite so sure about that. The prices have remained relatively stable, but the capacities have gone up. I think on a per Wh basis they may have actually gotten cheaper still. That means that you've gotten more battery life and/or more useful power in the devices that are using the batteries.
I will even venture that consumer lithium-ion batteries, such as for camera or laptop replacements, do not appear to have gone cheaper over last, say, decade. I can only assume healthy profit margin by brands (Nikon/Sony/Canon/etc, Lenovo/Sony/Dell/etc). Third party cheaper batteries are available, of dubious quality, so I suppose that may be a sign of cheaper manufacturing...