There are online stores on Easy.com that sell downloadable digital prints. I love this one from Cre8T which is only $7.18. You can print an A3 size poster of it at K-Mart for only $14 and buy a frame for $4.
You could print out a smaller copy for less. It would make a great gift or decoration for your room.
If your bedroom needs a makeover, consider a chalkboard wall (check with your parents first). A can of chalkboard paint will set you back about $15 at Bunnings. This one is from is from www.boredart.com.
Here is an easy holiday craft project - a butterfly collage. All you need is a photo frame, some scrapbooking paper, a butterfly punch and some glue. You can find instructions at www.theidearoom.net.