On a tangent to the https://www.homebuiltairplanes.com/...l-system/16252-cheap-efis-finally-coming.html thread, I have often wondered why no one is making a very cheap, simple HUD to replace basic flight and engine instruments for experimental and ultralights. And I mean simple, perhaps just a monochrome display of digital readouts and analog bar graphs for key instrument functions. The challenge is always keeping it simple without all the bells and whistles, but done right it could actually be cheaper than the equivalent analog gauges. I can easily imagine a light plane with little if any instrument panel, just a small console or side panels for radios and switches, and all the basic instrument functions on the little HUD. A properly collimated (focus off in the distance) display would be nice, but even a simple reflective display, the equivalent of one of those iPhone apps for displaying GPS info reflected in the windshield, would still help simplify and unclutter the panel. So, why is no one doing this?