Lifeline GPL-4CT 6VDC 220 Ah @ 20 hr rate.
Price about $270 ea with free shipping. Need two.
Compare this to the price of two Group 31 12VDC deep cycle batteries which have about 200 Ah total, if you don't run six volt batteries in series.
Over a 10 year period you'd go through 2 to 3 sets of wet cell Group 31 batteries, you'd have to check and add water each month and have to wash the battery compartment with baking soda a few times to deal with the acid. Murphy's law would have it that you have to change these batteries out at the worst possible time.
Or you buy a quality, deep cycle AGM battery and it lasts 10 years or more and you don't have to deal with any of the above.
The true lifecycle cost of multiple, cheap, flooded batteries vs. AGMs, really depends on where you want to spend your time

. I'd rather be camping with 110 Ah of useful capacity and only running my generator once every 3 days.