eCase via Amazon offers Prime members the Kmashi 600-Amp 12,000mAh Portable Car Jump Starter Power Bank for $59.99. Coupon code "59N6GLE6" drops it to $47.99. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $7.11.) That's $42 off list and the lowest total price we could find. It features an LED flashlight with three modes and advanced safety protection.

Update: Free shipping is now available for all customers.