I'd recommend starting with renting. If you like diving locally, you'll probably end up getting a drysuit. You could start classes in a drysuit, if your instructor is willing to teach an added class or two to also get a drysuit certification. The certification isn't necessary but its often included in purchase of a new drysuit. Plus, its a very helpful class, or at least I found it helpful.
I waited a long time to purchase a drysuit. I dove my first year exclusively in Puget Sound, in a 7+5 wetsuit, rented from the Army Base store. I wish I would have been able to purchase a drysuit for those dives!
Drysuits are now available at quite reasonable prices, some not much more than a high quality wetsuit.
For Caribbean diving- I usually start in a 3ml wetsuit in Bonaire with 80-84 degree water, but I almost always switch to 5ml after a day of repetitive fives, as I find myself chilling after the first dive of the day for the rest of my trip.
I think some parts of the Caribbean change temperatures quite a bit from summer to winter.
I need the heavier suit on night dives as I always seem to be colder on night dives, possibly because its the 4th or 5th dive of the day. When diving my drysuit in southern CA, I always add an extra base layer of Smart Wool on my night dives, even if I don't need it during the day.
our local diving in AZ allows for a 3ml or lighter in the lake during the summer but going below the thermocline requires a 5ml or heavier. I usually dive a 3ml for mid-summer and stay above the thermocline. In the fall I switch to drysuit and then I can dive at any depth that I care to dive.
Ive never purchased a 7ml wetsuit. Since leaving the NW, I found that a 3 and 5 ml have been perfect, along with adding the drysuit since living in AZ, because we dive So.Ca, where I prefer to dive dry. The drysuit is also great in AZ for anytime other than summer.
---------- Post added June 5th, 2013 at 10:29 AM ----------
What's great about ScubaBoard is that no matter how much experience you have or how much time you spend reading up on scuba diving theory and how many threads you go through here, you will always eventually run into something you haven't heard before.
Funny!
I asked a local shop person to show me any drysuit undergarments they may have in stock. I was shown the Lycra skins!
---------- Post added June 5th, 2013 at 10:50 AM ----------
Thanks for all the fantastic replies! I will definitely look into a 7mm suit at the very least. Going to check prices between Thermoprene and a dry suit.
it sounds like these are the recommended brands Hendersons, AquaLung, and DeepSee.
I had checked out a Scuba Network shop in Carle Place NY for an FYI on which shop I frequented.
I have a Waterproof 5ml and a Henderson 3 ml. Both very nice products. Around here, you can often get steals on wetsuits when they are on sale. I always browse the sale racks when I go to a store and I've picked up some awesome deals. Both of my wetsuits were less than $150. I think maybe even less than $100, but I can't remember for sure.
I also highly recommend a Lycra skin. You can slid into your wetsuit much easier and the Lycra is a great sunscreen topside when its warm. It also makes a great protective suit when water is extremely warm. I use it for my swimming pool diving a lot as it prevents sunburn and makes my gear feel more comfortable. Our pool gets up to the low 90s in the heat of mid-summer..
---------- Post added June 5th, 2013 at 10:56 AM ----------
Perhaps the salesperson was thinking of the difference between OC and CCR air? I've heard you stay much warmer using CCR, although I've never tried it.