Marvel Comics on Sale
The book category goes beyond what most people think of when they see the word books. Google Play also includes comics, manga, and more in this section as well (as long as it’s written content).
Marvel has a dedicated discount section for Android users here and you’ll see all sorts of issues (and sometimes entire series) flowing in and out of this area. Prices vary from a moderate level to unbelievably affordable so as always, check back often.