title_body: Many sites propose free or cheap ebooks? Which are legitimate?
upvoted_answer: The short answer is that any website offering permanent access to large numbers of copyrighted books, for very little money, from multiple publishers is unlikely to be legitimate.
  
  HumbleBundle offers its bundles for limited time.
  
  Book Barbarian, ManyBooks, BookBub, Luzme, and no doubt many others, search the web on your behalf and find books that are currently being offered from reputable sites, like Amazon and Kobo, for little or nothing.  Almost all of their free books are available only for a day or two, but in any case to get them you will have to click through to a recognizable merchant site.
  
  Then, publishers like Baen Books offer a large number of their e-books for free as loss-leaders. You'll notice that it's highly unusual for them to give you more than the first one or two books in a series, and the rest will cost you retail.
  
  Another clue to legitimacy is if the site offers payment in multiple currencies: there's almost no chance that any site accepting payment in US$, GBP and EUR is legitimate, because very few books are made available from a single distributor worldwide.
  
  All that said, if a site seems too good to be true, google that site's name and the names of some of the authors. Odds are they already know somebody's pirating their work, and they frequently rant about those sites on their own blogs.