Old jeans, old shoes, old white dress shirt (Thrift stores are money for getting Halloween gear). Purple Rit Dye, Green face/body paint, black face paint. (You don't need a lot of black, I just used a kit from walmart that came with a little q-tip like applicator for about a buck.) Green spray paint for the shoes, and a little muscle to boot.
Step 2: HULK TRANSFORMATION
Cut tear-like holes in pants and shirt. cut the pants off just below the knee and leave jagged and frayed. Dye the pants in Rit Dye. Spray paint shoes green. PAINT UP YOUR BODY (having a pretty girl help with the paint application is suggested ;) Paint face and use a little of the black paint to ad depth to the eyes and lips. Now go out and impress some folks!