I'm wondering how much skyrim will cost on boxing day?

More than it will cost in the January sale at ______. Wait a little longer, play with whatever you get for Christmas and then go out and get it from somewhere cheap.

Depends where you live.

You can check with the retailer where you are going to buy it from. At my local retailer (ebgames/gamestop) told me that NHL12 and Assassin's Creed: Revelations are going sale for 30$ and 40$, respectively. They are relatively new games so you can probably expect to get a good deal on Skyrim.

I doubt Skyrim's price will drop for a while, although they may drop it a little bit when Reckoning comes out.