This homemade Yoda costume was actually a really easy and really cheap costume to make but ended up being quite effective.
I bought a plain plastic mask from the costume shop (30p) and cut the bottom half of it off and built up layers of paper mache to form the ridges and shape of the head. I made the ears separately by cutting out ear shaped bits of card board and paper macheing them too and then stuck them on. I covered the whole thing in white paper and left it to dry and then painted it with green paint.
I bought a pot of green face paint (£2) and covered my arms, legs, face, chest and neck in it. I just wore brown shorts and a beige top I already had, with a long cream jumper as a cloak that I got from the charity shop for £3.
I made a light-saber from a roll of metallic wrapping paper (50p) with black tape wrapped around one end.