For networking a decent PC with proxmox can be the whole lab. If you can run a server and 2 client machines, that's enough for most network testing.
If you want to go full hardware a decent PC and two low end HP workstations running win 10 will do.
You can lab it all out in software or build various networks.
I'd look for used SFF dell, hp or Lenovo machines. Or just get a server that can run four VMs.
Change the logo to EdgeRupture. It sounds more painful. Very 90s marketing.