There's a ToysRUs savings pass for 15% off your entire purchase now thru Saturday 8-17 (the day before Infinity launch)
While there's also a 20% off infinity stuff coupon starting Sunday 8-18, that's only good for one item, so if you're lucky enough to find and pick up the third party accessories early, this is nice.
Also, if you read the fine print you'll even see that you can just show it on your mobile, nothing to print out!
http://j.toysrus.com/081113TRUHP
It's right on the ToysRUs homepage too
EDIT:
While it says "not good on Videogames and Videogame hardware", I've confirmed that Videogame hardware means the game consoles -- accessories fall into a different category.