Toolsmith Direct via Rakuten Shopping offers the Snap-on 1,600-watt Portable Digital Inverter Parallel USB Generator, model no. 871360, for $499.99 with free shipping. That's $200 off list and the lowest total price we could find. It features a 120-volt GFCI outlet, two USB outlets, and up to 2,000 surge watts of power. Deal ends June 1.
Of note, coupon code "SNAP10" bags 5,000 Rakuten Super Points. (They convert to an $50 Rakuten credit.)