Slickdeals listed a deal for 12v wire, 10 & 12 that was decently priced. You may want to grab a roll or two when it is on sale. Other than this, it is also good for speaker wire.
[50' GS Power 10 Gauge Dual Conductor Wire (Red/Black) - Page 3]
I’ve never used this brand, but I am picking up 2 rolls while on sale.
