There's a reason even used apo's sell for a premium and get snatched up fast. You web junkies can form
an opinion any way you wish. But those of us who actually use these lenses know why they're still in demand. And it isn't marketing hype ... never was. The other thing is that many apo lens designs had
well-known industrial and graphics applications all along, that ordinary photographers simply aren't aware of. And they're still being made for high-end industrial applications, though often in fixed aperture. If you want high-quality relatively affordably, Apo Nikkors are quite common, and will
beat the pants off most ordinary enlarging lenses, if you can work at f/11 with relatively large film.
They never made short focal lengths. Not to be confused with conventional El Nikkors or the very
expensive and now rare Apo El's.
I take it then that there is no online information or references regarding the El-Nikkor 80/4. Alternatively maybe you just meant the 75/4.