A GWh of pumped storage is $25M, a GWh of batteries is $100M.

More concretely, https://en.wikipedia.org/wiki/Fengning_Pumped_Storage_Power_... was built for about $50/KWh. Which is about the same price as batteries.

But that's a daily storage facility. If you undersized it's pumps so it took weeks to refill rather than ~10 hours to make it a seasonal facility, it would have been significantly cheaper.