Best small, desktop speakers, $500 or under (new or used)

That’s on the Zero.

@aburn -- thanks a lot! 

I do have to say, I am getting pretty exhausted with marketing hype. From the Vanatoo copy for $359 dollar desk speakers:

"The speakers reproduce music exactly the way it was recorded, with solid bass, clear midrange, and sparkling highs."

FFS.

Within your budget I would go for audio engine if you can get a pair of HD6 on the used market for a desktop system it is better to go with Powered Speakers mind you they can be a bit fatiguing But you get very good bass and crisp clear mind & Highs in a small listening  environment you will not need a sub ! You future proof yourself I got mine for $ 575 new so I am sure some on line dealers may offer discount pricing 

don't drive yourself nuts 
its $500  buy the first one that you think looks  ok.  move on ,  All the speakers 
outshine each other in different areas 

It's just that they're so old and perhaps mid-fi that I was thinking that maybe big advances had happened since, well, 1988, and I could easily best these things with even something well under $500.

I think you could trounce them multiple different ways for $100, for instance, with the Dayton Audio MK402BTX.