OLED is commonplace in 4K TVs now, but back in 2007, plasma was still the best display tech for the deepest blacks. That year, Sony unveiled the XEL-1, the world's first OLED TV. It was groundbreaking at the time. It also cost $2,500 for its tiny 11-inch screen and trash 960 x 540 resolution. Also, is it just me or does the XEL-1 still look hot 13 years later? God, I miss old Sony.

Yours now for about $899

The Light L16 camera was supposed to revolutionize cameras, combining 16 smartphone lenses and a bunch of periscope mirrors to replace a traditional barrel lens. The L16's 28-150mm equivalent focal length attracted photography nerds like myself. There had never been a camera like it. Unfortunately, poor performance, average image quality, and a $2,000 price killed it before it could kill DSLR / mirrorless cameras.

Yours now for $400

The original Fold was disastrous in every way. The design was half-assed with a laughably tiny outside screen, the plastic foldable display scratched easily if you looked at it wrong, and the $1,980 price was a huge turnoff. The first Fold failed spectacularly, but was innovative for a phone and did pave the way for the very good Z Fold 2. And now you can get one for a fraction of the original (albeit used).

Yours for about $750

Whenever Facebook and Apple get around to launching their AR glasses, they'll have Google Glass to thank for failing first. Glass may have been universally panned when it came out, but there's no denying that Larry Page and Sergey Brin's dream of combining the real and digital world using AR wasn't cutting edge. It was maybe too bleeding edge than people were ready for, especially at its $1,500 launch price. An old (likely non-functional) pair costs about $350. Google Glass 2 (for enterprise) is about $1,000.

Yours for about $350

Camera maker RED touted the Hydrogen One as the "world's first holographic media machine." I'll give RED credit for the tank-like design and mega battery. But in the end, the Hydrogen One's "holographic" display was really just a glasses-free 3D display (not too different from the one in the Nintendo 3DS.) RED's promise of turning the Hydrogen One into a cinema-grade camera never quite materialized (the mods never released and the phone was killed months after launch), but damn it if it wasn't ambitious.

Yours for less than $150

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