Mediabridge Products, LLC via Amazon offers Prime members the Mediabridge 16-Gauge Speaker Wire 100-Foot Roll
, model no. SW-16X2-100-CL, for $9.99
with free shipping
. (Non-members can spend $25 or more to qualify for free shipping; other shipping adds $7.24.) That's $10 off and the lowest total price we could find. It features a blue stripe to distinguish between left and right.