Use wiialerts.com, dude - there's been at least 4 opportunities I've gotten to the website in time for myself just today. (Gamestop, Newegg, Toys R Us and Walmart all pinged today IIRC for bundles of various sorts [no savings, but they weren't gouged either] - 100% sure on all but WallyWorld) But I want to wait for next month rather than doing credit/cashing in investments for the moment so I had to pass)
Just make sure you keep your smartphone on you and your information preloaded on whichever retailers you'd use and should be smooth sailing unless this was the last stock they'll get before Xmas (unlikely).