Oh so many aspects of photography require super expensive equipment. Fortunately though, Fireworks photography can be done with practically any digital camera that allows you to use bl settings. A simple strategy for fireworks photography is to set your camera on Manual mode, set your Aperture to f/11, your shutter speed to 4 seconds, and your ISO to the lowest native setting (typically 100 or 200). Use a tripod to keep the camera steady, and ideally use a remote trigger to minimize camera shake. Prior to the start of the fireworks focus your camera on a distant point and get sharp focus. Then set your focus to manual mode so the camera is not having to hunt for focus as the fireworks are going off.
With these preparatory steps in place, all you need is to now time your shots. Review your first shots to ensure good focus and exposure. Don't be afraid to shoot a little on the dark side. You don't want to lose the vivid colors of the fireworks due to blown highlights.
Here are some sample shots I took last night using these settings.