The one thing that I would buy is a new set of regulators. I don't like the idea of breathing someone elses halitosis. They will last for years with the amount of diving you are doing. Go to leisuirepro.com and look at the bargain regs they have. You can usually get a set plenty good enough for recreational diving for around $150. For another $75 or $80 you can get an octo. Considering what you will be paying for a liveaboard this is peanuts. You might want to go to a LDS and buy a mask that FITS. If you are sort of average-sized most masks will fit. Some dive operators require a snorkel also. No bigggee there, most will do. A good set of used fins can be gotten on Ebay if you have an idea what you want. Same with wetsuits. They can be bought new or used at rediculously low prices on Ebay. If they don't fit exactly, get out the scissors. It's not that important. If you are diving in warm waters you might not even need one. BCD? In general a pretty useless piece of equipment as far as I am concerned though required by most dive operators. But for a new diver who doesn't know exactly where to place his lead weights for correct buoyancy they make things a little easier. Same thing, shop around. They are extremely over-priced as new. Used mostly to stay off the bottom and, with some air in the bladders, to stay on the surface. Don't even think about buying tanks or weights. Booties, hoods, gloves, etc? Cold water stuff. I personally don't use them except for gloves when going down a down-rope. You should buy a safety kit with a whistle, mirror and surface marker buoy. Cheap and required. You might want a nice knife in case you are attacked by a shark or killer octopus. They are usually pretty cheap too.