Regular drill bits will work fine as long as you go slow and easy - especially when you are about to "break" through the other side. Dull bits work better. The bit the salesman was trying to get you to buy was actually a bit designed to scrape the plastic instead of cutting it. The angles are different on the bits. Also, when using screws to join your pieces together be sure to drill your holes slightly larger than your screws. This allows for some movement of the plastic and prevents breakage at the stress point.