I bought my screw in the hardware-store for around 0.30$.
You also need a drill with a 5.5mm diameter size. 6mm might also work.
Step 1: Drill a hole in the bottle-cork
Step 2: Insert the screw
Step 3: Attach the bottle-cork to the camera
Fill the bottle with some water to make it steady an you're done!
Please visit www.hobbyman.se for more tips (in swedish)