I have my advanced open water and am getting ready to get nitrox certified. I've done about 60 dives..everything from local lakes to Cancun to Rio de Janeiro (Brazil)..
Some of what Idol says is true. Some is not.
He's correct about (for now) just buying what you need for the class. Rent the rest until you figure out what you really wanna do.
I'm taking my girl friend to Play del Carmon (20 minutes outside of cancun) on June 16th (7 days, all inclusive (including alc drinks)). She got certified this past summer. You can darn tooting we are doing some dives...but...the only gear i'm actually taking is the basics (no bcd, regs, dive computer).
Like Idol says, you can rent all that stuff. Why lug it around, risk it getting stolen/damaged?
Also, always wear some sort of skin protection while doing salt water dives. There is just to many things in there that can scratch/cut you (not even talking about fish). And as you will learn in class, water does suck the heat right out of your body...
Now then..for the "not true" parts.
Since you are taking scuba lessons, I'm going to assume there is someplace near you to dive, probably lots of lakes and even some rivers.
I live south of Houston, right on the gulf of mexico. My house is maybe 500 yard from the gulf of mexico. I launch my jet ski at a marina that is so close, I can see the mast of the sail boats.
Yet most of my dives are freshwater dives....local lakes and stuff.
Assuming you have stuff like that around you also, you will probably have lots of opportunity to dive in the future.
Sooo..as you dive more..and get more experienced, you will figure out if you really like it or not (i LOVE it). If you go enough, your going to want your own your wetsuit and BCD. (note, people DO pee in those rental wet suites...!)
The BCD you will (probably) use for the class and the ones they rent are NOTHING like the "good" ones. Once you try on one of the "nice" ones, with integrated weights and stuff...well, you get the point.
Same with the regulators and dive computers.
It's all going to depend on how often you go diving, if you "keep" with it..and of course your budget.
Like any sport, there is without a doubt a start up fee. (how much is a good set of golf clubs??). But once you buy them, you don't have to do it again for a long time...
My advice is to join a local web forum. You can ask/find a lot of local people who can answer your questions..also about local dive locations.
I'm sure there are a lot of people here who dive also...ask any questions you want.