I have a fairly large collection of old books (some of which are out of copy right).
I'd like to edit a few of them and sell them very cheap. I imagine they would be good for discretionary left over btc but I'm not sure if even then people would be willing to buy.
If you're selling them on the dark net it doesn't matter if they are out of copy right date or not. You can still be convicted of several crimes because you are contributing to a criminal enterprise. I would bet that you are incredibly low on their priorities but it's something to keep in mind