I was thinking of using Raspberry Pi's ... that I have laying around.
Discussion
Yeah don't need much CPU/RAM to run a node, just enough storage. My unpruned blockchain at home is about 500GB.
You do need a static IP to run a lightning node, which is why I'm using a VPS.
I had to request a storage quota increase from Google because they limit you to 500GB disks by default. It only took about 15 minutes to get approved for double that.
Server storage is SPENDY though. If you can manage to set up a static IP at home that would totally be the way to go.