Yeah - Old EBay server equipment can be had for like $200/node and will burn at least that much in electricity every year :-/ Also, the noise is hellacious!

Old laptops / desktops can be better - especially since you can get newer/more power efficient units without all the noise. But I started moving to even smaller SBC based stuff (0)

0: https://ameridroid.com/products/odroid-h3