Red Dead Redemption GOTY $15 for Consoles on Amazon

Red Dead Redemption Game of the Year Edition for XBOX 360 and PS3 is on sale right now for $15 at Amazon. It includes the standalone expansion, Undead Nightmare. Red Dead Redemption got fantastic reviews but I'm not really a cowboy western fan. Undead Nightmare looks fun though. I wonder if it's worth buying for that alone.