Toys "R" Us offers the Sesame Street Flying Super Grover 2.0 for $9.98plus $9.99 for expedited 2-3 day shipping (standard shipping costs $7.99, but probably won't allow Grover to be a part of your Christmas). That's $7 less than the lowest total price we could find to have it delivered before December 25 elsewhere. He moves his head and arms, sings and talks, makes various sound effects, and requires two AA batteries (included).
Don't need Grover for Christmas? Mills Fleet Farm has it for $10 plus $7.95 for shipping.
Update: It's now available for in-store pickup only.
Mill's Fleet Farm cuts up to 55% offclearance toys, with prices starting from $3.90. (Click on the "Toys" link on the left side of the page to find them.) Even better, all items are eligible for free shipping. That's the first such sale we've seen from Mill's Fleet Farm and leaves many items at the lowest prices we could find, some by significant margins. Some best bets: