That's one stack of redstone ore. Not that much, like I said from one stack of ore you would get about 2.11 dust. And Cadmium certainly isn't economical to produce, but if you don't have much lithium then it's not *that* unreasonable.
At low tech level its still grunt work, which means if you wanna sit around and spoon-feed machines for 25k extra storage per battery (@ LV), instead of shore up your power grid / generation capacity you're pretty daft - the time wasted spoon feeding those machines can be spent making steel for turbines, or even mining to get hold of better ores.
Besides, salt veins are pretty common in my experience and those stack up with mixed lithium ores (spodumene and lepidolite).
Like i said, Cadmium is simply not worth it for the time and energy (EU) you would spend getting hold of those extra few storage points, you're much better off searching for lithium / lithium by-productable ores and advancing to MV to make use of them.