This is a great price. I haven't tested the Eco Worthy, but they have decent reviews. To get the price just find the item on ebay:Ebay has eco worthy 12v 100ah for $312/pair ($156 ea) until 3/18. free shipping.
ECO-WORTHY 12V 100Ah Lithium Iron Phosphate LiFePO4 Battery (2 Pack 100ah)For RV
and use the coupon code which showed up automatically for me: SPRINGSAVE20