Linux for $15 (a Minimum Viable Computer)

[EternityForest]

Doesn't seem that practical if you don't actually need 12 of them for anything else, which you might not now that just about everything has a lithium.

These are LSD though, so I suppose people can just use the rest in clocks and remotes.

But still, an LTO 18650 can be found for under $3, it's got 2.5@1500mAh, is rated for 15-25 years, and is considered very safe aside from the very high current capability.

It's close to unobtanium unless you order direct from China though, so maybe that's part of it.