Walmart offers the Black + Decker 500-watt Power Station for $68.98 with free shipping. (Amazon has it for the same.) That's the lowest price we could find by $49. It features 450-amp/900-amp peak jumper with metal clamps, six gauge cables, and LED emergency light.

Update: Note that Amazon now has an estimated shipping time of one to two months.

Update: Note that it's no longer available at Walmart, however Amazon still offers it for $68.98 with free shipping, exclusively for Prime members.