Re: power inverters
At least 700 watt continuous. If you watch the department store sale flyers you can usually find a 700-750 watt continous/1500 watt peak power inverter for ~$50.
Anything more than that and you should consider buying a small generator. A small generator from 20-30 years ago usually runs on a 3.5hp motor or so and has a 1000 watt continous/1500 watt peak head on it. I have one I run the house on to keep the furnace going. I picked it up for $50 or something about 5 years ago. It's quieter than a pushmower.