Ask HN: What's something that doesn't exist that you would pay for?
Something your company needs? Something you personally need? Could be anything you would pay money for!
As explained here --
http://arachnoid.com/Sangean_ATS-909X/index.html
-- there is a gap in the shortwave radio market, between the radio the article's about (a reasonably good radio with some limitations) and the high-end Icom radios (superior). While researching the article, I was astonished to discover that there simply aren't any shortwave radios in the gap between an economical but limited radio at one end, and an excellent but pricey radio at the other.
It's an unmet market need -- hard to say how big, but the potential customer base is definitely nonzero.