Best Power cable around/prefer under $300....

I can easily explain this for you, based on some insider talk I know for sure: Peter, the guy at The Cable Co., which is the owner of Used Cable website, used to work for many years for Synergistic Research. Which means that’s where all SR surplus go first.

Also, typically, high volume manufacturers, not just cable manufacturers, tend to have much more listings on used market than low volume manufacturers. Similarly, low volume manufacturers, not much available in used market. This is just a fact, reality.

After listening to and enjoying lesser cables, from both Kimber and Synergistic; they were sold to make room for and finance their upper crust wares.       No difficulty quickly moving anything I've owned, from either company.         Mostly: here.                        It's doubtful that I'm alone, in that practice.

Clarity Audio Vortex...over $300
https://www.dagogo.com/audio-blast-clarity-cable-organic-and-vortex-series/

Also, typically, high volume manufacturers, not just cable manufacturers, tend to have much more listings on used market than low volume manufacturers. Similarly, low volume manufacturers, not much available in used market. This is just a fact, reality.

@thyname

Not sure I understand this logic...so this is where all SR surplus used cables go first? Makes no sense. Where does used surplus come from and what’s the difference between garden variety "used" and "surplus used"? lol

Furthermore, about the "low volume manufacturers"....Audioquest has 2 listings, Cardas 1, and Shunyata has 3. Not sure SR (and its 11 listings) is bigger than any one of these companies and certainly not bigger than all 3 combined.

Edit: In fact I just looked up information on SR. They have approx 15 total employees and operate out of a 12,000 sf warehouse. That’s honestly a much smaller operation than I had even assumed. Comparatively AQ reports to have 135 employees. 

Cullen Cable sells direct with a trial period, so you can try their 6ft Crossover cable that sells for $199 in your system to see if it works.  Underwood HiFi has their Valiant Silver cable at around $180 that might also be worth exploring.  Audio Envy has been gaining quite a following here so they’re definitely worth a look too.  Best of luck.