Harmonic Tech is good for high quality UPOCC copper cable at reasonable prices. It's the same company as Neotech so they are the actual manufacturer of the cable. I sell HT cable at good prices btw.

The Pro-11 reference cable is $35/ft in bulk. Notice it uses 8 runs of wire per leg with PE insulation... much better geometry and insulation vs most less expensive UPOCC SC.
https://zenwaveaudio.com/product/harmonic-tech-pro-1113-speaker-cable/
For less $ I'd suggest trying surplus mil-spec wire from Apex Jr. 12g stranded is about $.60/ft, a star quad (4 runs twisted) would be 9g equivalent. You can make the star quad with a drill, just be careful to keep the wires nice and straight before twisting.
If the mil-spec wire works for you it's excellent, far better vs most lower quality copper wire. The silver plating can be an issue in some circumstances in terms of sounding bright or splashy, so trying a shorter length 1st might be a good idea. Also, if it doesn't work for highs it'll probably work fine for woofers so you could use this for the woofer run and biwire with something like the Harmonic Tech Pro-13 for the highs, which is $28/ft in bulk.
http://www.apexjr.com/wire.html