The Lithium Iron Phosphate (LiFePo4) battery in the Solarpod 240 is rated for over 2,000 cycles. With a lead acid battery you're lucky if you get 500 cycles.
So which battery is cheaper? Well, you'd have to buy four lead acid batteries to get the same cycle life as just one LiFePo4.
While better technology usually comes with a higher price tag, if you compare the cost per cycle between lead acid and LiFePo4, you'll save a ton of money buying the better technology.
Oh, yeah, one more thing. LiFePo4 is better for the environment, is non-combustible, and holds a charge longer so it actually works when you need it. There's nothing cheap about a dead battery.