Paint samples are really cheap (cheaper at Lowes than Walmart). Grab a blank canvas (also cheap), use painters tape to make a design, and buy a size appropriate wooden letter, or smaller letters to make a word, and paint those= Awesome art.
Brightly painted frames, cardboard letters and loud scrapbook paper. (or, wooden frames, cardboard letters and muted scrapbook paper, which is what I was actually planning to do on the nursery wall once the baby comes and I know initials!
DIY-All you do is buy the picture frames, and use whatever colored paper you would like to make it pretty. Put the class on it, and then you can write on it. I would put this by the door going out so then you'll know what you have to do for the day.
DIY Bulletin board and storage drawers to spice up your dorm room/ bedroom! - using permanent craft glue sticks glue fabric cut to size on the inside of the drawers with right side facing out to show through translucent drawers.