[strike]This is the best under $100, but not very good for gaming: http://pcpartpicker.com/part/asus-video-card-r7250x1gd5[/strike] EDIT: Check andrei65's post.
But as the article mentions, the cheapest gaming graphics cards are considered "Entry-Level." However, the cards in the article should do the job just fine considering your price range. There are several of them, so look around and see what you're willing to work with.