I got both 123s and L91 for about $1/each; C cells for about 0.25/each and D cells maybe 0.40 each.
Off topic, but the really cool thing about Malkoff 3D is that you can fit 4xC in it for more brightness and lighter weight.
I got a really good deal on about 600 alkalines, I think I won them for 2-3 cents each plus SH. Then when the package arrived, I discovered they were actually that "heavy duty" Carbon-Zinc garbage.
To make lemonade from the lemons, I found out that they run wonderfully in MiniMag with SMJLED conversion (Or Nite-Ize) or PT Apex on Low, or anything else with a low drain. The run time s*cks for sure but bang-per-buck is actually pretty good. I already gave away a few hundred to friends/relatives but still have this enormous depot of non-alk AAs. I wonder if I can donate them somewhere for Chrismas, but my guess is, they wouldn't run kids toys very well at all due to the heavier load.
If anybody asks you, where you buy your batteries, the correct answer is, I don't buy batteries, I *have* my batteries.
Back to the OP, I think 50 cal ammo cans are good to store stuff in. Also they make 30-cal ammo cans that are smaller.
All this Lithium or Li-Ion stuff is no joke, have to be careful with it. There is a lot of chemistry in these boxes.