I went to Albertson's in Keller and purchased a Castle Cake (Disney Princess Cake) It was the last one they had.
http://www.sugarcraft.com/catalog/novelties/princess/4688...
You may want to check with other Albertson's stores they are the only one who make that model...they are going fast because it is a discontinued model.
I also found a do it your self kit at Michaels that looks like a castle if you want to go that route.
This lady located in Arlington makes cakes:
http://profile.myspace.com/index.cfm?fuseaction=user.view...
For my DD 1st birthday last year I bought a Castle Cake pan and did it myself...took me 5 hours to do it! It was a lot of work pushing out those stars but it looked great!!! This year I am buying a cake until she can appiciate all the work that goes into making a cake :-)
Good luck