Welcome to the 'Board, soxgirl! When you take into account everything that you'll need to purchase to get certified, it should run you between $600-1200. This will depend on the price of the course, price of the gear you must purchase before class (mask, snorkel, fins, booties), the course manual, rental gear for the check out dives, boat fees if there are any or entry fees to the dive site. Then after you get certified you need to consider the gear you will need to purchase or rent in order to continue diving. Scuba diving is not a cheap sport, nor should it be. The equipment you use is life sustaining. The training you receive is also life sustaining. It's a fun sport, but it can be expensive. My wife and I have spent well into 6 figures since we got certified...but then again we do specialized diving that cost even more than your basic recreational diving. 
