Cheap to buy old hardware, but electricity to run those old rigs isn't really cheap in many areas now. My server is costing me about $100/month in electricity costs.
It does have 16 spinning disks in it, so I accept that I pay for the energy to keep them spinning 24/7, but I like the redundancy of RAID10, and I have two 8-disk arrays in the machine. And a Ryzen-7 5700G, 10gbit NIC, 16 port RAID card, and 96GB of RAM.
I’ve been watching some storage and homelab-themed videos and I heard there’s a lot of optimizations you can do to lower power usage - spinning the disks down, turning the machine on for a limited time, etc.
It depends on the type of hardware that you use for your server. If it's really server grade you're totally right. For example cheap memory+CPU+MB x99 off AliExpress are cheap but they're not very efficient.
In my case I fell in love with the tiny/mini/micros and have a refurbish Lenovo m710q running 24/7 and only using 5W when idling. I know it doesn't support ECC memory or more than 8 threads, but for my use case is more than enough
How have you measured the power usage/cost? That seems like a incredibly high price for electricity, similar to a 600W constant load in my part of the world.