They start at expensive and go up. Even banks of lead acid batteries are expensive, but at least in a fixed location weight isn't a big problem. But lead acid batteries have to be changed out about as regularly as you change out a car battery, and this application calls for deep discharge batteries, like marine batteries.
Battery storage is expensive enough that standby generators tend not to use them. They come on and burn fuel as long as grid power is out. But if you size it for peak demand, then on the low demand end it uses more fuel than perhaps is needed. The result is that, after a natural disaster, you can run up an eye popping fuel bill pretty quickly.
Example: A propane powered standby generator sized for a residence can use 2 to 4 US gallons of propane per hour, depending on the load. Let's call it 2.75 and assume most of the time it's not peak demand. Power is out for a week. That's 168 hours. 168 x 2.75 = 462 gallons. At $3 a gallon, that's $1,386. But something fun: Fuel companies only fill propane tanks from 80% to 85% capacity to allow for gas expansion. Once saw a over-filled tobacco barn propane tank overpressure valve vent, so it does happen. So a 500 gallon tank only holds 400 gallons. Oops. So we're talking less than a week of power unless the propane company can make a delivery, which is iffy in a natural disaster. A 1,000 gallon tank would be good for about 290 hours at 2.75 gallons per hour, and that's 12 days. Post-Helene, it was 16 days before we got all the lines back on, though most had power restored in a week. If someone had run a backup generator the entire time, that's 1,056 gallons of propane and a $3,168 bill for the propane alone.
This gets into how often a Helene scale event happens and how long you're willing to be without power. Have seen ice storms knock out power for days, so it isn't always a hurricane. Bottom line is that if you have to replace batteries several times on the average before a long duration event, it might be cheaper to pay through the nose for fuel.
That's assuming you're allowed to have fuel in the first place. That's straight-up politics, but can see that happening.