Well, I think the carpet goes with your theme. I would be happy with the carpet, then paint the walls a purple a few shades darker then the carpet. Then get black sheets and a black or black and purple bed spread- or either of the movie ones if you want to get more theme-y.
I know there are lots of Tim Burton stuff at Hot Topic, and here is a few of the stuff I like.
Action Figures http://www.hottopic.com/store/product.asp?LS=0&ITEM=623301
And at Hot Topic do a search for Corpse Bride Bust-Up and there 5 or 6. They could be put on a shelf, and are probably fun to make.
Since Nightmare Before Christmas is a little older, you may have to look around other places like ebay.
Also, if you're aloud to put up posters, I've seen posters for both movies at Spencer's.