Disney Sing It: High School Musical 3 Senior Year For Wii
It’s released on Dec 5, 2008.
I live in the US and have not heard of this game here. I don’t think the US stores carry it on stock. The only place i have seen this game at is at the UK amazon store, and I don’t think they ship to the US.
You probably can’t find it because it isn’t out yet. Wait another couple of weeks and it’ll probably be everywhere.