I use 4 Lenovo M910x's as a kubernetes cluster and home lab. Have them all connected with a netgear switch. The whole setup costs about the same as a single new quality work station. Each has: i7 8700 (6c - 12t), 32gb memory, 1TB SSDs, <1L case, they're practically silent. easy to find parts, they even use lenovo laptop chargers. if one dies, I can easily purchase + replace in a few days.
You can even go cheaper if you don't need the absolute fastest cpus. Some of these older tiny computers can be purchased for around 100 bucks if you look for them. It has worked like a charm for me. Not sure how much horsepower you really need, but this is a cheap way to build a home cluster. I think they hover around using 40w most the time, so power isn't really too big of a cost either.