If I go to Blockbuster, I head straight for the 4 movies for $20 table. Otherwise, our local library actually has a good selection for free, and it has some available at booksales. Also, resale shops and gargage sales are a good source. My latest find was at a resale shop for $1.
Oh, I'm member of the paperbackswap.com. Great deal for books. Well, they have a sister site for DVDs. My intent is to try it out. Have any of you used the DVDswap site?