I'll be the first to admit that I double-bought Mirra 2. I got it originally for GameCube, but found that there were several bugs that shipped with it (apparent memory leaks, addressing problems, collision dection, among others), but I was willing to take a $5 chance on the XBox version that by hardware principles, would have most of these problems cleared up (and it did).
I've actually purchases many more than several $5 (or less) games in the past year, and enjoyed more than the majority of those that I've had time to play. $5 won't get you a rental at Blockbuster, but if you would even be tempted to try it out, it doesn't hurt, (unless you start running out of space). Since being a part of this scene, the only time I was in Blockbuster was to pick up Max Payne 2 for $13.