For my homemade Beetlejuice on Rollercoaster costume, I started off looking for black trousers and a blazer.
I then bought white Contac paper, cut it in slices and taped and sewed the paper to the suit. I bought vinyl for my hair and white, green and black paint for my face. Then I bought a couple of black and white cardboard pieces to create the rails of the rollercoaster. I bought three sheets of Styrofoam to construct the rollercoaster support.
Finally, I watched a Beetlejuice trailer to see how the rollercoaster mine cart looked. I pasted some yellow paper on a cardboard box with glue. I spent about $15 on my entire costume.