I partly disagree, when you say "buying from an online store" do you mean you are buying already assembled mining rigs?
No,Actually, I bought all hardware of mining in the online store or offline store in a way part by part, I never bought in a way the package (that have been assembled).
try to find used and cheap mobo, ram, and hdd etc. they do not make much difference on mining speed. keep them "bare bone". The less spending, the faster roi.
yes, half my hardware (motherboard, RAM, SSD) except PSUs, USB Riser, and GPUs is almost all "new" but not for now
