Where to purchase cables?

I use this company: https://www.bluejeanscable.com . Their products and service are outstanding IMHO.

Audiogon, US Audio Mart, TMR Audio, The Cable Company. 

Frank at Signal Cable has Great cables at very fair prices . I use no other anymore!  sales@signalcable.com / 917-957-8508

I bought my 4-conductor 12 awg OFC bulk speaker wire from Monoprice, and DIYed them.  Amazing bang for the buck.

Cables I get almost anywhere - custom made local guy, Amazon, Audiomart, Ebay, AliExpress, Craigslist, FB Marketplace, Reverb

For my main system I tend to purchase from my dealers. They will let me audition, but most are Transparent and I have most recently upgraded to the most recent. I usually keep old interconnects and use on my secondary systems. Upgrade your main system and use old ones on.
 

But for a secondary system I would go to the Cable Company… you can get used for half price. You can try also from their lending library. I am not a fan of most of the budget brand… I have found most to be no better than what comes with the component or you get at Best Buy.