Christmas present for my sister?

My sister is 17 (turning 18 in Jan.) and some of the tings she wants/likes are water polo, poison ring, Disney movies (Aladdin, Hercules, Up, etc.), and a mermaid bag. She doesn't wear a lot of make-up. She can be super nice at times but then super mean. I have no clue what to get her! I was thinking a woolly mammoth from Build-a-Bear because she said she wants that. Any ideas? They also have to be cheap. Limit $30