I've heard of this demo before, but have no idea what its worth

 

It could be rare, but usually they have little value and float at 3-10 dollars. Even in cases where something special is in it they don't command much.

This disc was only available at Toys R Us. As far as I know, none were physically bundled with the Wii. I remember my local TRU selling the discs for about $5 each, and also  giving the same disc away for free with the purchase of a Wii console. So I think there is only one version of the disc and sleeve, and that they all look like this: http://nintendemos.com/?id=game&a... .

As far as value goes, it's a lot harder to find one than it is worth anything, but mainly because there isn't really demand for it.

 

It's hard to say. I'd say maybe you can get $20-$25 from the right person.