The PC's PSU will need SATA power on its cables or else you'll need to scavenge a separate PSU and use the paper clip trick (or better yet, a purpose built connector) to get it to power things on without a motherboard connected.
Once you have all of that, then it's just a matter of housing the disks. People have done this with everything from threaded rod and plastidip to 3D printed disk racks to used enterprise JBOD enclosures (Just a Bunch Of Disks, no joke).
Total cost for this setup, excluding the disks, can easily be done for less than $200 if you're patient and look for local deals, like a Craiglist post for a bunch of old server hardware that says "free, just come haul it away".
Check or r/DataHoarder on reddit or ServeTheHome's blog
If it was just one, I'd put it down to random bad luck. But with that many failures I assume they are doing something stupid/cheap.
Usually they would simply fail to power on but sometimes individual slots seemed to die (which RAID just loooooves).
And having an entire enclosure fail and waiting days/weeks for a replacement sucks as you lose access to all your data.
I eventually bought a Jonsbo N3 off of Aliexpress and PCI SATA card (to support more than the 2-4 drives most motherboards support) and that has been working well for months.
There is one deeply troubling flaw to them though, they don't turn back on of the power goes out, until you physically hit the button again. I think this is alas all to common for many of these enclosures!
