I need ideas for my room...?

Im 14 and im tired of my plain room, I want something fun. I really like pink, green, and brown. Im really into dirtbikes and horses. I have a twin day bed, a dresser, a bookshelf, and a big table thing. I have horse posters and motocross posters up on my walls. But I need something new and inexpensive so if you have any ideas please help!