I went into work late and stopped by Best Buy on the way. HZD rang up for $39.99 ($49.99 - $10 for GCU). I showed them the online price on my phone and they price-matched it for $19.99. I didn't get anymore off for GCU, though. After $10 reward cert, I walked out with it for $10 out of pocket.
Nice! I'm so glad I saw this thread. My 360 just died and I was debating whether to look for a used fat 360 or get a new slim. Now, I can just get a slim and use my old hdd. Perfect!