Need copper speaker cable recommendations $300 ish

This is a little more than what you want to spend but Chris at Blackcatcables.com makes some well reviewed cables.
https://blackcatcable.com/collections/speaker-cables/products/coppertone-speaker-cable?variant=20126386880571

There’s also Zu Audio speaker cables that are a steal at the prices they’re asking for on eBay:
https://www.ebay.com/itm/Zu-Audio-MISSION-Loudspeaker-Cable-Mk-I-8-ft-banana-to-banana-New/133480694798?epid=17029676900&hash=item1f1411c40e:g:5zsAAOSwnGFfJGEY

Both make their own cables from scratch. There’s more out there so take your time and then decide.

All the best,
Nonoise

There's a company called HCM Audio in the US, they are currently offering closeout deals on Audioquest GBC and GLC speaker cable sets, a 8ft pair of the GBC is listed at less than $150 terminated. They are also listing "Extreme Silver" IC cables at about 1/4 of the original prices, just to give  some idea of what you might save. I believe the cables are stocks of cable types made redundant by upgrades in the Audioquest line, and bought up by the retailer but are still regarded as genuine Audioquest.If the GBC is the same cable that was superseded by the Gibraltar when Audioquest went over to the DBS system for their higher end cables then it's an excellent cable. I have no connection with either company but have been using Audioquest cables for many years. Not sure where you are (if) in the US so I can't comment on taxes and delivery costs. 

Isn't there a cable company in the US that allows you to try cables at home and return them if you're not happy? I seem to recall one many years ago and wishing that we, in the UK, had access to a supplier like that.
Good luck with the search

Visit VH Audio for both quality bulk cable and made-up cables. Another very good supplier like PartsConnexion but with different merchandise.