What a wonderful niece you are! I was thinking more of a combination of what others have suggested. Throw in some consumables, i.e. rotary blades, marking pens, glass head pins and add a gift certificate to a local store. That way she has something to open but can use the gift card later for something special.
Another thought, if you know where she shops, they may already know about what things she might need or like.
One last thought, a gift to both of you would be to ask her to teach you how to quilt!