Manga doesn't cost that much (about
400 yen each) but amounts to quite a bit when you are looking for a whole set. I a recently went to Book Off to look for a whole set of manga and took some old magazines in at the same time to see how much they would buy them from me - they paid
100 yen for a few old copies of New Type which was more than expected. Rather than throw out the mags on magazine-recycle day, I now take them into Book Off for the next fellow otaku to enjoy.