All of the furniture (mostly family pieces) was reused, the decor just got streamlined and bit more Big Kiddish.
As far as cost was concerned, we only bought a gallon of paint, a new quilt ($30 at Marshals), and 3 12 x12 frames (40% off 3 visits to Michael's!) to frame our Barbie fashion art.
Plus a new light fixture ($30 at IKEA).
Most of the fun stuff from her first room just got slightly redone in the new room.
In the world of room swapping, just remember that now that the Homey room is done, there is an office/playroom living in the Fireplace Room and a master bedroom to move. No rest for the domestically weary!