I think an easy way to personalize a room is to find a color scheme that she likes and then get a simple comforter (I noticed Aldi has some on sale next week) and buy some fabric and make cute throw pillows. You could make tie backs for the curtains out of the same fabric. Unless you find fabric on clearance, it's probably cheaper to buy the curtains (hopefully on clearance or sale). What I like about this is that it's much easier to change the "accents" if she grows tired of them, and you can keep the colors the same.

Also, Walmart is usually cheaper than Target, and I've had good like finding clearance at Penney's and places like that. Maybe Kohls? I even found some at Big Lots before.