If you're looking for a bargain fridge battery Itechworld have their 54ah lithium on special for $200. Less a $20 voucher for first time customers. I've never seen them under $450. Before.
https://itechworld.com.au/collections/lithium-batteries/products/itech054-12v-54ah-lithium-ion-battery-lifepo4-deep-cycle-recycle-camping-rv-solar-slim-line