I have a 3000 watt 12 volt AIMS Power inverter for sale. It is brand new - never been removed from the bubble wrap before I took the photos of it. I bought three of these units in September 2010 and only ever used two of them in my house. These units run my lights, 'fridge, freezer, TV sets, computers, battery chargers, well pump, furnace blower and various shop tools, drill press etc with no problem. Microwave oven buzzes more than with pure sine wave when using these inverters.
Its FLA draw is 300 amps, and I've measured the DC->AC conversion efficiency at about 95% at 250 watts AC draw. It has 30 amp battery charger and automatic transfer switch. Requires 30 amp 120 volt AC input from your generator (or grid) for full pass-thru power. This unit has the remainder of the factory warranty left on it (to September 2011). $400 for it and I'll cover the shipping anywhere in the continental US.
--
Chris
Edit: This inverter does NOT have a "floating" neutral. The neutral is bonded to ground inside the inverter per NEC and your subpanel is wired to meet code with the neutral going to the neutral bar and the ground going to the ground bar in the panel. The inverter's chassis bonding stud is bonded to your service entrance ground, or separate ground rod for off-grid applications.