Depends on the quality of what you want. Each person is different. You could buy stuff online and hope it works, void the warranty, but get a good price, or go to a dive shop and try it before you buy it.
My costs were, and I was on a budget for the most part
Zeagle scout BCD $325
Body glove wetsuit $160
Mares mask $68.00
Scubapro Snorkle $35.00
Twin Jet Fins $161.00 (There are plenty of way cheaper fins)
Deep See boots $44.00
Gardening gloves $5.00
I have always rented my regulators, but will be buying one soon and I think that will cost me the most. Can someone recomend me a cheap but good regulator and the best place to buy it?