VACUUM SAVINGS via Amazon offers Prime members the Haul-Master 12-Volt Magnetic Towing Light Kit
with free shipping
. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping adds $6.17.) That's the lowest total price we could find by $16, outside of the price below. It includes includes a 20-foot wiring harness and double-sided lenses with amber flashers.
A close price: Harbor Freight Tools offers it for $11.99 plus $6.99 for shipping via coupon code "63251089". Sales tax is added where applicable. Coupon expires March 31.
Amazon Prime membership is $79 per year; however, Prime is free for college students for six months, and free for parents and caregivers for three months.