Renting a DVD/Blu-ray disc doesn't cost much. But does buying a used DVD/Blu-ray disc. Now unlike renting, once you buy a used DVD you can get the value of your money back by exchanging your DVD for another. And if you have a large number of friends the $5 you spent on one DVD will get you more than 20 DVDs and at the end of it, you'll get your DVD back and add it to your collection. Which of the two would you prefer? Buy a used DVD or rent and watch it ONLY once? IMHO, buying does save you money in the long run.