Homecoming dress help!?

I have a black sleeveless dress that comes to my knees, but since it is sleeveless, what can I put on top, to not show my shoulders? I have a yellow cami, but it is too casual, and I don't want to wear a black cami over it. what should I do? My price range is really low. around 15 bucks if I need to buy something. please help!