With electricity prices being what they are right now, a Raspi using <5W is fantastic for me.

My current Docker host is an used Lenovo ThinkCentre M900 Tiny I bought. It's got a 65 watt power supply and it's definitely not using all of it.

i5-6500T, 1TB of M.2 SSD, 16GB of ram and running a good two dozen Docker containers.

I'd say that's a better bang for the buck than a closet full of Raspberries struggling under the load :)

65W would represent about a 30% increase on my average electricity usage or about £15/month, probably more later this year. HA is the only thing I run locally, and I mainly use it to save energy - also for watering plants and scaring foxes out of the garden.

I know it isn't going to be pegging at 65W but if it's anywhere in the vicinity, it's cheaper to use AWS instead. I used to have a server that I used for Plex/HA, but in the end the energy cost was higher than a Netflix subscription. I could have upgraded it to more energy efficient hardware but it would have taken years to pay off.

I agree - a used corporate small form factor PC from the likes of HP/Lenovo/Dell has tons of power for HA and can still be had for a next to nothing. They also sip power - under 10W at the wall at idle.

I think an old laptop in the home network would work well