I think this is a misunderstanding. The Redflow batteries have...

I think this is a misunderstanding. The Redflow batteries have more energy storage capacity than many Li batteries, so an individual battery may be more expensive, but not when equal capacities are compared. When you further take into account that Li batteries lose capacity over their life, and that Li batteries should not be fully discharged (even regular 80% DoD will probably not be helpful to long battery life), while RedFlow batteries can be 100% discharged on a daily basis without affecting battery capacity or longevity, the equation may be quite different. Also, Redflow's cost estimate is for a complete system including battery, inverter, and solar panels, and this is often compared with the price of a Li battery alone - definitely not an apples to apples comparison.

It's also true that volume manufacture of RedFlow batteries is really only just getting under way, and availability is likely to be pretty limited for the remainder of this year while the company prudently handholds early installations.

https://www.solarquotes.com.au/battery-storage/comparison-table/