Duvet cover or sheets?

There is a cute pattern that I’m in olove with at PB Teen. But I have to choose between the duvet, http://www.pbteen.com/products/p3326/index.cfm?cm_src=rel , with brown sheets or the sheets, http://www.pbteen.com/products/p3328/index.cfm?cm_src=rel , with a brown quilt. What should I do, because I have limited funds so I can’t get both.

I like the duvet- I have a duvet and all I use is the sheets on my bed- and my duvet. Duvets are great because they don’t keep you too hot or too cold. Also, the one you have is gonna be pretty cute!