Last year after Rita we were without power for four days. The first two days we didn't even have a generator. I spent all of my time using inverters and car batteries just to keep my tanks alive. In the end, we lost two starfish because the tanks got too hot... We were fortunate; it could have been much worse. If you can afford a generator, they're lifesavers~!
I recently saw them advertised at Home Depot. They ranged in price from around $1500.00 to $10000.00