Buying your own mask, fins, booties and snorkel(if you use one) are pretty much a gotta have. I personally like having my own regulator, computer and buoycompensator. I was a warm water diver and kust packed a "Skin" type dive suit when we travelled. I hated diving cold water and haven't been in it in a long time. Diving in the Caribeian, South Pacific spoils you for sure. Buying used gear is probably the best way to accumulate your stuff as people go in full blast, then for whatever reason they bail. It sets and they pretty much give it away, even when they hadn't planned on it.
Terry