Drive is almost full, whats next?

Heya all!

Like most people who've gotten seriously into Plex, I've done some upgrading since starting. From a 2tb to my current 20tb drive, the media hoarding impulse continues.

I'm down to only 4tb free though, and know sooner or later (probably sooner) that will get stuffed too. So I'm wondering: what's the next move? The aim is low cost/low expertise. I'm considering a multibay external enclosure so I can (possibly) shuck my external and have a place to put it. But do I want just a bunch of drives? RAID? A NAS seems like an idea but more expensive? I also have zero experience with RAID setups.

Taking all suggestions in my self-hosting journey :)