Alternative to leather shoes

First of all excuse my english but Im not a native speaker. I have this question about what alternatives do one have for the leather shoes. Im trying to get a sharper look in the casual context, as Im a colege student, but dont like to wear leather made shoes and accesories because of my philosophy of life.

PD: I like very much the chukka/desert boot style, can you give me some tips on what to wear them with.