Appropriate Gift Ideas for students?

I am a school bus driver and I have about 9 kids on my bus. One boy brought me a 1lb of Fannie Mae chocolates, a girl brought me 3 gl cups one was broke and the other students have yet to give me anything. I am trying to figure out what should I give the students if anything. I don't make very good money so I'm not sure what is appropriate to spend. Oh I forgot to mention one girl gave me a horrible cold my throat is on fire! What a lovely gift to be sick on X-mas.