I bought my son, he was 12, and my 10 year old daughter gear. They both got computers-can't outgrow those. Then because rental bcd's are hard for the small guys, I got Zeagle Scouts. You can change and adjust Zeagles and they have smaller lift capacity bladders so they are easier for them to control. They both have Scubapro twin jet fins and good masks- keepers through adulthood. Then I got regs for them. In all, only the wetsuits need replacing as they grow. And I got Henderson for those. My lds is really very good, in that when Haley grows out of her adult small Zeagle-though tiny, she fits it fine with all the adjustments you can make to the fit, they will trade it with me for difference in price of a Ranger. Same with Justin. It is a great deal. I have traded wetsuits once already. They get to put them into their school gear and I get a great break. By the way, the Scouts are really inexpensive. The highest end item was the reg and those should last.
good luck