What is the cheapest way to attach a few external drives to my Small Form Factor debian home server?

I have powered USB 3.0 hub with lots of ports. But not all my drives have enclosures.

I have 2-4 each of 3.5" HDD, 2.5" HDD and 2.5" SSD sitting idle. All SATA. Ideally I’d like to get at least 4 of them attached.

All the hardware I can find on retail (docking stations, enclosures, towers) are really expensive to buy enough of them. Is there some sort of cheap, ugly way to do this? The cost of buying enough enclosures is more than a regular sized PC from my local tech non profit. Should I just buy a new computer? I have spent a lot of time setting this one up, I don’t want to start fresh.

Are enclosures interchangeable if they are the right size and connections? I have some old/small external drives in my junk bin. Can I swap in the larger drives into the old enclosures?

Don’t need NAS, RAID or anything. Just straightforward access to my files.