In the UK the calculus is quite different, as it’s £0.25/kWh or over double the cost.

Also, an empty Synology 4-bay NAS can be gotten for like £200 second hand. Good enough if you don’t need much performance. Mine draws about 10W compared to an old Optiplex that draws around 60W.

With that math using the NAS saves you 1.25 pence per hour. Therefore the NAS pays for itself in around about 2 years.