If you are thinking in the long term about cave training, why not start out with the gear that you would use to do that? You can get a backplate and wing setup from Deep Sea Supply for about $450. Or our local dive shop is offering a package deal with a DSS backplate and wing, Zoop computer, and a Subgear reg analogous to the SP MK17 (I think) for $1500, or with a more basic regulator for $1000.