The most important equipment that you need, and it comes in many varieties and sizes. Why is it so important? Well first of all SAFETY! Many discs that pet stores offer, can be dangerous to your dog's well being. Stay away from hard plastic promotional discs or just plain discs that are sold in toy stores. These can and will often shatter increasing the chance of cuts and punctures to your dog. Here are some recommended sites to go to buy and learn about discs and disc types.
If you plan on vaulting your dog, you'll need to invest in one of these! These can be purchased new or used from some scuba shops. Used is preferable because it is a whole lot cheaper. Some people use life vests, but I prefer a thick wet suit vest. It provides more protection for your body, and is a much better platform for your dog to vault from. This one can be zipped.