You might be forgetting another source: used books. There are literally millions here. Used-books shops are everywhere, sometimes there are entire streets taken by them. You can find anything here, and everybody commutes about an hour from home to job, the perfect time to read a book.
Also, anything more expensive than a book (tablet, e-reader, phone) will get stolen and you beaten, so settle for the old book.
Also, anything more expensive than a book (tablet, e-reader, phone) will get stolen and you beaten, so settle for the old book.