Great advice from NorthWoodsDiver, who has recently been there, done that. I'll add a couple of thoughts. A long-running thread about 'most regretted purchases' had many similar gear comments, and NorthWoodsDiver gives a 'spot on' summary.
NorthWoodsDiver:
Take a look at where you intend to dive most, who you will be diving with and what type of diving you intend to do now and in the next couple years. ... I am diving a 7mm 2 piece wetsuit now but since most of the water I dive in doesn't get much above 55 degrees F than I should have gone the drysuit dirrection. If you go wetsuit look into the extra strech material, I spent lots of extra cash and got hendersons titanium hyperstrech material and its worth every penny.
If you're in FL and plan to be there a while, you should be fine with a good 3mm WS. Don't hesitate to spend money on a good exposure suit, like the hyperstretch. After the mask/fins that should probably be your first purchase. Get something that fits, is comfortable for you, etc. Maybe I'm getting to be a woos but if the water temp drops below 70, I go dry. I own a Microprene, a 3mm WS and a drysuit - no 5mm, certainly no 7mm. If you plan to dive in the frozen north, or return there in the future, keep money in the budget for a good DS. I just find it much easier, and warmer, to dive than thick neoprene.
Strongly echo the BP/W sentiment - going BP/W from the start makes very good sense for all the reasons given - equivalent cost, greater flexibility, will 'grow with you', adaptable for virtually any dive environment, etc. You'll find many people who swear by their BC, whatever brand/type, and this is not a criticism of their enthusiasm and experience. Once you try a BP/W it is unlikely (not impossible, just improbable) you'll ever want to return to a BC. If you do go BP/W, don't go with expensive harnesses to start. Try simple webbing for a harness and see if you like it - it is inexpensive and very functional. You can always go with a more elaborate harness down the road. Also, even if you are diving wet to begin, go with a SS BP. It may allow you to minimize weight on your waist, or eliminate it altogether if you dive a steel tank.
NorthWoodsDiver:
I like fins that are neutral or slightly buoyant and high viz after seeing 2 people loose a fin in lake superior one day.
Good good points to heed. If you dive wet, chances are you'll not want a negative fin. I love my SP Jets for my DS, but I prefer my Mares Quattros for wet. My 0.02 - go with spring straps from the outset, whatever fin you get. No sense in worrying about straps breaking at the wrong time.
NorthWoodsDiver:
I went with the common aluminum 80's and am switching to Faber FX-100's which are high pressure steel (might go with worthingtons also, undecided).
Again, a common exprience. The AL80 is the most commonly encountered tank. But, go HP steel when you are ready to buy a tank and you won't regret it.
While I don't think a computer is essential, nor should it be an early purchase, I do like the log functions (as NorthWoodsDiver mentions) and the computer adds to my available information. I still use tables, to maintain proficiency. If you go with a computer, defintely get a nitrox-capable unit.
NorthWoodsDiver:
Stay away from spare air systems and the like. I have one and carry it for now on solo dives but only until I can afford a 19 cuft pony setup, than the 3 cuft spare air is going on ebay to kill someone else. Every LDS I have been in pushes the spare air so watch out.
Very worthwhile. Many folks mentioned regrets about the Spare Air, and small pony bottles. FWIW, the general sentiment was nothing smaller than 19, but a number of people said nothing smaller than 30. I started with a AL40 as my pony. It is remarkably unobtrusive on a dive, has plenty of air, and I ended up converting it to a deco tank when I went tec.
NorthWoodsDiver:
I dont like renting ... if you dive regularly and want the warrantee than go new and go quality.
To a certain extent, there's even a safety issue. While many operations rent excellent gear, there is something to be said for owning your own gear, early - you are familiar with the equipment and its function, you know its history, you know the service record. That reassurance simply reduces one of the elements of stress that can contribute to UW problems. Gear ownership contributes to more frequent / regular diving. More frequent / regular diving contributes not just to more enjoyment but to greater proficiency. Greater proficiency contributes to better safety. These are not absolutes by any means, but definite trends.