Best Desktop Speakers under $500

"Best" is always subjective, but Wharfedale and SVS would be on my audition list in this price range.

Audioengine makes a line of passive and active speakers in that budget and style.

Wharfedale should fit the bill. This place has a 60 day return policy in case you don’t like them!
https://www.musicdirect.com/speakers/wharfedale-diamond-225-bookshelf-speakers

Also, you need to decide if you want active speakers (with a built in amplifier) which would be more compact for the top of a desk, or if you want passive speakers, which will require an amplifier, etc. 

Definitely check out Q Acoustics.

Triangle Borea BR02

On your desk, or in your office? 

I’d consider active biamped monitors with 5" drivers if on desk; get some nice litle stands like IsoAcoustics. The Mackie CR5X has a cute green trim; well in budget. The IK MTM would be a step up for nearfield from the built-in DSP and D'Appolito layout.

Decware tiny radials

https://www.decware.com/newsite/TinyRadialProject.html

i would see if you can find some Airpulse powered monitors used or Edifiers... there should be something in your price range. I have the Airpulse A200 and they are world class midrange..

Too bad those Decware tiny radials aren't active. They're beautiful to look at and would fit in any decor or setting.

All the best,
Nonoise

They don’t make the best anymore. I’ve got mine.
I will note that the Aon 3’s go lower, are more efficient and are less costly than the Wharfdales are.
However, nothing equals self powered bi amped, like an Alpha 50 Evo, on up.
https://www.crutchfield.com/S-1du46bwi8CX/p_091FA50EVO/Focal-Alpha-50-Evo.html?XVINQ=GLX&awkw=13...

I am on my second set of Klipsch Pro Media 2.1 speakers.  For $129.00, I haven’t heard a better desktop speaker. 

I'd consider these.

https://www.accessories4less.com/make-a-store/item/kefq150wln/kef-q150-5.25-2-way-bookshelf-speaker-...

If you like the VA sound these are a bargain, not much bass though.  I significant step up in quality than new speakers at this price.
https://www.ebay.com/itm/304132125228?_trkparms=ispr%3D1&hash=item46cfaff22c:g:LgQAAOSwPnthMlyS&...

Audioengine makes a line of passive and active speakers in that budget and style.

I tried their small actives and was unimpressed. I like fine detail in the top end and these were too smooth. My very old Wharfedale Diamond 6 sound much clearer.

As I am unable to make my “desktop dream setup” a reality (Croft Integrated & Harbeth P3ESR), I’ll have to live with my current set up.

Minimus 7 speakers (I upgraded the crossover to the Ziltch circuit) and once I’m done rebuilding it, a 4 watt EL84 based Heathkit SA-3 integrated will be driving them. 
As it stands, these ridiculously inexpensive speakers sound far better than they should. There is a reason why these cheap little things have such a cult following. The xover mod made a night and day difference.

Not fatiguing in any way, shape or form.

Aside from the questions about powered/passive etc,  , how much real estate do you have for the speakers? Footprint, both real and visual, may have some limitations.

+1 dbtom2. Audio engine is the bomb- small but full. They may come in white.

Radio Shack Optimus Lineaum speakers. EBay is your friend. 

My Audioengine 2 desktop speakers started showing their age (many years now) with an irritating buzz coming from the left speaker that's getting worse with time so I, too, have been looking for a nice replacement. Glad this thread came up. 

Just now, I came upon this video from YouTube, recommended from all the research I've been doing. Looks like you can get a nice assortment to choose from apart from the Audioengine and Kanto lines that seem to be so popular of late.

It's hard for me to decide.

All the best,
Nonoise

Love my gorgeous powered Audioengine 2+ in red gloss finish with included stands. Those on the desk, paired with cheap subwoofer on the floor, all under $500 not counting the high-end cables that came free from the Currently Disused Cable Drawer. You feel the fresh breeze in your face when the 3" woofers kick in. (That said, I did no comparisons before buying. When now-or-never discount offer hits your inbox, you just buy and don't look sideways).

Wharfedale Denton 80th 

The Kef Q150's that Jon_5912 suggested would be nice in a smaller room. The coaxial tweeter is great in close quarters.
They are not powered speakers, if it matters.
Here's the link from Jon_5912's post:

https://www.accessories4less.com/make-a-store/item/kefq150wln/kef-q150-5.25-2-way-bookshelf-speaker-...

Goodmans Maxim, from the 60s.
You can just about find a good pair for $500.

Hello,
I think you should go with the PSB AM3s for $399. If you can find the AM5s used that would be your best bet. They retail for $599. They are powered and have several inputs including a phono stage. Also has Toslink, Bluetooth, and line in. And just in case you do want better bass it has subwoofer out. One and done powered speaker system.  Plus, All Paul Barton speakers are really good. I heard them at this store in the Chicagoland area:
https://holmaudio.com/
this store will let you try them before you buy them in your home. 

The Vanatoo Transparent Zeros are quite nice. Stands would be recommended to get them up off the desk.

I have the Vanatoo Transparent Zeros and for the price I don't think you can do much better.  The smaller Audioengine and Kanto powered speakers look nice but they really need a sub to help with the lower frequencies.  The Vanatoo's really have an advantage with the passive bass radiators. Highly recommend.

No love for the Elac Uni-Fi at $599?

Logitech makes some good speakers for computers check out this link https://www.logitech.com/en-us/products/speakers/z906-surround-sound-system.980-000467.html enjoy 

Find a used pair of Adam A5. Active. Ribbon tweeters. Better than all of the others I have had (lots of computer speakers, home audio monitors {Polk, Dynaudio, ...}, Monsoon planars, Audioengine, Swan M200 various versions). Each of the above did good things.

The Adam A5's do a lot of good things. The bass is very good and the ribbon tweeters are oh so good in a nearfield desktop system.  They can also play loud enough to fill a small room if you are not at your desk. 

Use an external DAC if this is a computer based system

OP, I assume you mean powered speakers but please clarify if that assumption is incorrect.
I would say the SVS Prime Wireless, Vanatoo Transparent One Encore, Edifier S2000MkIII, Kanto YU6, and Audioengine A5+ (Plus) are the better choices at that price point.

Mine. ;)

1. Edifier G2000 Stereo Speakers.
2. Logitech Z207 Bluetooth Computer Speakers.
3. Cyber Acoustic Portable USB Laptop Speaker.
4. Bose Companion 2 Series III Multimedia PC Speakers.
5. Cyber Acoustics CA-3810 Computer Speakers with Subwoofer.
6. HP Gaming Speakers X100

Just an FYI if anyone's still looking: check out your local BestBuy for a returned, open pair of Klipsch R-41PM speakers. 

I went darn near crazy checking all the reviews and videos and saw that these are considered a great buy for a desktop system. Going deeper into the rabbit hole I came across them for $280 ( returned but in excellent shape) and hurried my butt down to get them. They work great and are a bargain compared to what it would cost to get another pair of Audioengine A2, or anything close to them.

All the best,
Nonoise

If you are willing to stretch the budget just a bit, I recommend used Kef LS50s. I use them to great effect.  They face my kitchen, so do double duty to keep me entertained while I destroy good food.  

I see them available now between $600-700.

Used Canton GL 260. Recap them with good caps. Still way better than most of the new bookshelf/desktop speakers.