Amazon has the Dewalt DCB1800B Portable Power Station on sale for $299.00. Normally sells for $399.00
The DEWALT DCB1800B flexible portable power station is designed as a 4 port parallel charger. This 1800 watt portable power station operates with four 20V MAX* batteries in, 15 amps out. (Batteries sold separately). Take cordless power anywhere! Specifications: MAX AC output 3600 watts / rated AC output 1800 watts. MAX current (120V/240V) 30 amps / rated current (120V/240V) 15 amps. Required Number of batteries - (4) 20V batteries. Indicator lights: inverter and charger, operation and fault, low battery.
I have one of these and while it seems expensive, this thing is awesome. It is essentially a powerful 110v power bank. I have found numerous uses for it and if you already have Dewalt tools and batteries it is a must have accessory.