If you use Ryobi 18V tools, this is an incredible deal. Six 2Ah batteries and charger for $129. Could be useful with the 18V inverter for small device backup power. Found at
Buy 18V 5000Ah Li-ion Replacement Battery for Ryobi ONE+ Tool RB18L50 P108 P107 P122 P104 P105 P102 P103 Cordless Drill Power Tools at affordable prices — free shipping, real reviews with photos —