Got an 18tb from serverpartdeals for 160 I think.

YAMS.

https://yams.media/

Not perfect, but if you just want the ding dang thing to start so you can see what a working setup looks like, then bam. Use yams.

I use Kavita for my comic book collection, and recently added some books into it as well. Syncs well across devices. I don’t really read books as I have so much time to listen to them instead but I can’t see why it wouldn’t work for someone who does.