Most divers today consider themselves lucky to see sharks because sharks are becoming so rare. Like most marine animals, sharks are usually frightened by the bubbles made by a scuba system and swim off almost immediately upon encountering divers. Normally, sharks must be enticed with food before they will interact with divers. If you ever encounter a shark that looks threatening, stay toward the bottom and swim away slowly. I hear it's expensive.
Equipment is an important part of scuba.
High quality, properly maintained equipment not only provides us with the ability to visit the underwater world, it gives us greater safety while doing it. You probably won't be much of a diver if you do not buy scuba equipment, just as you wouldn't be much of a skier if you never bought skis. However, scuba equipment is rather expensive. So most dive centers offer equipment rental as a way to allow their students to purchase equipment over time. If you can afford to purchase some of your equipment during your training, your PADI instructor can assist you in mastering how to properly use it.