Best RCA interconnect up to ~$100?

I'd check Pine Tree Audio ...

https://sites.google.com/view/pine-tree-audio/interconnects

AudioQuest Golden Gate are around $140.00.  Have a pair coming today for my new Mofi Turntable coming next week.  I have read good things about those cables.  We will see I guess. They have to be better than the 20.00 cables I have laying around right?

You can’t go wrong with Blue Jeans at your price point. Also, I’ve had good luck with custom cables made by performance audio in Salt Lake City. Great to deal with, lots of wire & design options, and high quality.

https://www.performanceaudio.com/collections/custom-rca-to-rca-cables

For really well designed, high quality parts, hand made cables made with pride and passion for the Audiophile space, check out Pine Tree Audio.  Call Jessie and he’ll recommend the design best for you based on your sonic preferences and system.  Check out Pine Trees site, read some of the reviews and do yourself a favor and call, tremendous value and you won’t need to upgrade down the road. 

OP,

I have used and can recommend: DHLabs (not White Lightning), Morrow Audio (50% sale right now), Supra Cables Trico or EFF RCA cables (dealer selling on eBay), or Pine Tree Audio which are showing promise. All could get you a very nice RCA pair that will grow with you through to "mid-fi". A couple might cost a little over your $100 limit, but only by $20 or $30