If you buy a 16 cells to make a 48V battery than yeah the vast majority of the cost would be the lithium cells, a 16s 250A BMS should be around 150€, an active 16s balancer 50€.
You also need an inverter, a high-quality 8-10 kW unit could approach a thousand euros easily.
I was talking about making a battery, if you want a full solar installation then you also need an inverter, charger, MPPT.
Not sure why you got downvoted.
Its high value-add, but I would have thought competition would push prices down too.