This article is from the Scuba Diving FAQ, by njs@scifi.maid.com (Nick Simicich) with numerous contributions by others.
There are two schools of thought on this. One is that you should
consider only purchasing your personal gear until you are sure what
type of diving you like. This school believes you should buy only
mask, fins, and snorkel, for fit and sanitary reasons. The other
school of thought is that the rental gear you can rent, especially in
tropical locations, is second rate and poorly maintained, and that
gear you purchase will be better and more reliable. Typically, people
agree that you should not buy a tank until you believe that you will
be doing a significant amount of local diving.
 
Continue to: