There is no extra cost to have hot swappable unless you're considering buying consumer grade hardware, but consumer grade hardware is more expensive to host because it won't fit in 1U bays.

> Do you believe you're getting redundancy when you go with hetzner and a cheap desktop grade processor, ddr4 non ecc memory, and a consumer grade SSD?

Irrespective of how much I'd skimp on the hardware, I always have a HA setup, including on EC2, so it doesn't matter in any case.