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

No idea if they’re the best but I had a pair of Audio Engine A2 that I liked, What Hi-Fi gave 4 🌟. They make larger sizes, passive or active. And wireless or not. 

Silverline Minuet best .

For small footprint, I got a set of Q Acoustics Concept 20 and supported on IsoAccoustic stand (they do fit). Good compromise/balance of price, quality, and small footprint.

Not sure if they’re the best, but they sound good to me in office setting (generally lower volume). With volume turned up after hours the small size is a limitation (12’x12’ office driven with about 45wpc Micromega MyAmp) but still maintain good sound quality.

I'll also recommend buying used, best bang for the buck, generally 95% reliable/safe in my experience, but takes a lot of searching and time.

Is this the speaker you were trying to post a link for?

http://www.ascendacoustics.com/pages/products/speakers/cbm170/cbm170.html

Never heard them but the measurements on them are really good for a small speaker. 

Someone mentioned the RS minimus 7. Those are good, but there is a real hidden gem in the RS line up called the Optimus Pro LX-4. This is a ported Small bookshelf  speaker with a 4” Kevlar woofer and a lineaum tweeter. The imaging on these speakers is great, but if you spend about $20 to mod them, you will be amazed at how good these speakers sound. Considering that these routinely sell on EBay for $50 or less per pair, they may just be the audio bargain of the century. I’m not saying they’ll definitely outdo Every pair of $500 speakers out there, but there are plenty of speakers in that price range that these will hold their own against. I have a pair of these and have used them as near field and they excel at it. Take a chance on these. I guarantee you won’t be disappointed. 
Read this: https://www.blackdahlia.com/tipindex/Tip__3/tip__3.html

It has the mod instructions in the article too.