Well, just about any class you take will require that you own your mask, snorkel and fins . . . consider that a give.
My personal preference of the order in which gear should be purchased:
1: Thermal Protection
2: Buoyancy Compensation
3: Regualtors
4: Computer
Here's why:
1: Your thermal protection (wet suit, dry suit - whatever is required for your diving environment) will keep you warm. If you're trying to complete tasks while you're cold, you won't be concentrating on the task at hand because your COLD!!
Secondly, getting cold can bring about the onset of hypothermia - this is not a good thing.
If you get cold, you won't want to dive.
Your thermal protection is also a very critical piece of equipment when it comes to mastering buoyancy. Moving about different wet suits, etc., will keep you guessing as to how much weight to use, and so forth.
2: Your B/C, need less to say, plays a paramount role you mastering your buoyancy skills. Different B/C's have different levels of inherent buoyancy.
It also helps to know where all the needed knobs are when you need them. Using a myriad of different B/C's leads to confusion as to where certain things are. Having your own promotes the quick learing of locations of things on your rig. This is especiall important if an emergency arises.
Now, eliminating the adverse conditions of being cold, inherent differences in buoyancy from various combinations of thermal protection and B/C's helps you master your buoyancy control much, much, more quickly.
3: Regulators are next. While all regs don't breathe exactly the same, any reg will supply you with more than enough air during your dive, given we're talking about recreational diving.
Regulators can get pricey. But really good ones, with proper service, will last a lifetime.
4: Computers are nice, but not necessities. You probably did your training with an SPG, depth gauge and compass console. That setup can allow you to dive any dive you want.
Computers get pricier than regs.
And until you determine what type of diving you'll be doing, you really won't be quite certain of which type to purchase.
Well, that's just my OPINION . . .
Others will jump in to help, also, I hope.
By the way . . . "WELCOME ! ! !" to ScubaBoard.
Safe dives . . . . . . . . .
. . . and safer ascents !
the K