That is the Super Size Disney Princess Castle Cake Kit, and it is no longer available. I even checked ebay.
I thought so--darn!
Sorry. From amazon it looks like it was discontinued in 2009.
I HATE these silly manufacturers that come up with something catchy for kids, but they only have one production run at the factory. And that's it.
I went through something simiilar when a friend's kid wore out his Peter Rabbit bed set. I went to every fabric store in a wide area and searched online, and never found the same pieces again.