I don’t think selling e-books is legal, if you have physical copies of BALG books, there’s a kind of a waiver on selling your own personal stuff on here, but not digital content obviously.
As for what you SHOULD do, try the Book of Fate, Q.s 8 & 9 are the cosest it has to Yes/No, or Q. 27.
Personally I probably wouldn’t do it because I’ve had several books bought on the off-chance that waited patiently for years before the moment I was ready to use them, I think you’re still too early into your own studies and practice to know for sure what’s not for you and that you could be kicking yourself for parting with anything that will be more expensive to buy back further down the line. 