I’m farming with used computers. Here is my setup.
10x HP 600 G3 i7-7700T tiny computers (65W ea.)
1x Fujitsu W550 as my main
2xFujitsu W550, Fujitsu TX1320 M1… To store plots. About 250TB and 360 TB more coming next week.
I’m pretty happy with this. Making about 10TB a day. My only big problem is managing to plots.