I think the author mentioned only spending $449.73USD (i can't verify because the sites down), which seems cheaper than what you mentioned.
I'm also struggling to find exactly what you're talking about. I'm seeing 9020's, but no M, do they actively sell it still?
I'm not nitpicking your comment - i too am interested in throwing a couple Pis in a closet for some distributed systems projects i'm working on. I expect them to be slow, low bandwidth, but simple over wifi/etc. I don't want to pay more than i need for closet computers, though, so i'm interested. :)
~450 eur in total, I bought all of them used.
But most of the price came from maxed out ram and quad core cpus.
For something cheaper, I can find in my country lenovo tiny m72, for something like 40 eur. No SSD/Ram, you can configure it as you wish (and still will be cheaper then RPi, even after adding like 2GB of ddr3 - it's something like 4EUR per stick, there are 2 slots in each machine).
That is with Intel Core i3-2120T, so would expect much more performance then even RPi4
Edit: I see now that the same seller has them for ~72eur with 120GB of ssd and 4GB of ram if someone wants something ready to use.
I think the author mentioned only spending $449.73USD (i can't verify because the sites down), which seems cheaper than what you mentioned.
I'm also struggling to find exactly what you're talking about. I'm seeing 9020's, but no M, do they actively sell it still?
I'm not nitpicking your comment - i too am interested in throwing a couple Pis in a closet for some distributed systems projects i'm working on. I expect them to be slow, low bandwidth, but simple over wifi/etc. I don't want to pay more than i need for closet computers, though, so i'm interested. :)