As far as equipment, I personally didn't buy any of my own equipment until after I was certified, and had been diving a bunch of times.
But, as someone else mentioned, some places will give you a discount on the classes or the equipment, or both if you get certified with them.
Either way, all of the stuff isn't exactly cheap. And, you can always rent equipment from a dive shop until you decide on exactly what you want to buy. It's pretty cheap to rent a whole setup. There's lots of divers who don't own any equipment, and just rent it.
Or, you can start of with (gently) used equipment. Sometimes you see really good dive equipment sales on Ebay or craigslist, where the whole setup was only used twice, for whatever reason.
I bought almost all of my equipment used, from dive shops down in the Keys. I'm assuming that the local dive shops sell off their used equipment too.
My advice: start off with a good mask and fins, then work your way up to a BC and regulator (that's the expensive part). Figure out your wetsuit size and the one you want (a thick one if you're diving in New York) and shop around ebay for that.
I think the same rules for reef tank equipment apply for dive equipment- don't rush, and don't skimp, it will just wind up costing you more money later to replace it.
Just my 2 cents
Hope that helps! good luck!
