It was when I posted, used items show in the right side column. For example if you go to:That D10s is 109, not 65. Was it some sort of 'flash deal'?
https://www.amazon.com/KGUSS-Discrete-Headphone-Amplifier-Pre-Amplifier/dp/B0B4JRY19Z/ ($449)
Lower right they show the used price in the box. The last one for the D10s was probably bought within 5 minutes of posting by someone.

On that note, here's some eBay stuff to mix it up a little. None of these eBay listings are mine. All are buy it now with good set prices for what they're offering. Be careful of the Sennheiser IE900 on eBay currently. There's a liquidator with six listed at "too good to be true" prices and I doubt someone selling household goods and Amazon returns just happened to get six of them. For the IE900 fakes, things to look for:
Nozzles on real ones are black, not grey.
Tips on the right side have flat faces, if they're all rounded over it's a fake.
On the cable, the logo is a hologram in the light on real ones, fakes are painted logos.
DROP + Sennheiser HD 8XX $677

DROP + Sennheiser HD 8XX Flagship Over-Ear Reference Headphones (HD800) | eBay
What is it?<br><br>DROP + Sennheiser HD 8XX Flagship Over-Ear Reference Headphones (HD800)<br><br>What is the condition?<br><br>Open Box - Like New Condition. <br><br>What is included?<br><br>The headphones with an original cable. There is no storage box. Pictures are of an actual unit for sale...
www.ebay.com
TOPPING A70 Pro $399

TOPPING A70 Pro Fully Balanced Headphone Amplifier | eBay
Used this excellent amp for about 2 months until I upgraded once again.
www.ebay.com
Beyerdynamic DT 880 Headphones (250 ohms) $99

Beyerdynamic DT 880 Headphones (250 ohms) -TESTED | eBay
Find many great new & used options and get the best deals for Beyerdynamic DT 880 Headphones (250 ohms) -TESTED at the best online prices at eBay! Free shipping for many products!
www.ebay.com
JDS Labs Atom Desktop DAC/Amp Stack $120

JDS Labs Atom Desktop DAC/Amp Stack | eBay
<p>JDS Labs Atom Desktop Audiophile DAC/Amp Stack</p><br /><p>You’ll get the following:</p><br /><p>DAC</p><p>Amp</p><p>JDS Labs RCA cables</p><p>Power adapters</p><p>USB cable </p><br /><br /><p>Original packing not included </p>
www.ebay.com
Audeze LCD-X 2021 $695

Audeze LCD-X 2021 Version open back headphone | eBay
Audeze LCD X 2021 version. Absolute pristine condition. Bass is sublime. Just an excellent sounding headphone with unimaginable resolution. At least to my ears.
www.ebay.com
beyerdynamic dt 700 pro x $125

beyerdynamic dt 700 pro x closed back headphones | eBay
DT 700 Pro X closed back headphones. Perfect working condition.
www.ebay.com
S.M.S.L THX SH-9 $175 (they sent an offer already for that so they'd accept it)

S.M.S.L THX SH-9 XLR/RCA Headphone Amplifier | eBay
<p>In like new condition. Comes with the original box, remote, and power chord. Feel free to ask any questions. </p>
www.ebay.com