30 kg / 108 = 0.27777777778 kg per book.
So for 150 books: 150 * 0.27777777778 kg = 41.666666667 kg.
And for 29kg of books: 29 / 0.27777777778 kg = 104.4 books.
I think there will be soon. It took probably years to make the Warrior series like this, so Seekers will probably take as long. Just wait and there will be one. There is already Seekers book 2 out.