Stopped by my local Wal-Mart this morning and they still had their 20 GB Xboxes at $350.
Best Buy is offering it at $300 (plus it comes with Need for Speed for free) along with Future Shop (their deal comes with Gears of War and Dead or Alive: Xtreme 2). If you're intested in a protection plan as I was, Best Buy's plan is slightly cheaper than Future Shop's.
When it comes to the free games, I recommend double checking with an employee and making sure you get everything rung out correctly.
I went with Future Shop's deal myself. For just over $400 I ended up with the 20 GB Xbox 360 Pro, Gears of War, Dead or Alive: Xtreme 2 (which I'll totally never play, by the way), a three-year protection plan, and I picked up Fable for the original Xbox as well.
I'm pretty pleased. I just hope I don't regret not waiting for the 60 GB.